From the Doctor Who episode Journey's End transcript:

DONNA: I thought we could try the planet Felspoon. Just because. What a good name, Felspoon. Apparently, it's got mountains that sway in the breeze. Mountains that move. Can you imagine?
DOCTOR: And how do you know that?
DONNA: Because it's in your head. And if it's in your head, it's in mine.
DOCTOR: And how does that feel?
DONNA: Brilliant! Fantastic! Molto bene! Great big universe, packed into my brain. You know you could fix that chameleon circuit if you just tried hotbinding the fragment links and superseding the binary, binary, binary, binary, binary, binary, binary, binary, binary, binary, binary, binary, binary, binary. (gasp) I'm fine. Nah, never mind Felspoon. You know who I'd like to meet? Charlie Chaplin. I bet he's great, Charlie Chaplin. Shall we do that? Shall we go and see Charlie Chaplin? Shall we? Charlie Chaplin? Charlie Chester. Charlie Brown. No, he's fiction. Friction, fiction, fixing, mixing, Rickston, Brixton.
(This time it hurts.)
DONNA: Oh, my God.
DOCTOR: Do you know what's happening?
DONNA: Yeah.
DOCTOR: There's never been a human Time Lord metacrisis before now. And you know why.
DONNA: Because there can't be. I want to stay.
DOCTOR: Look at me. Donna, look at me.
DONNA: I was going to be with you forever.
DOCTOR: I know.
DONNA: The rest of my life, travelling in the Tardis. The Doctor Donna. No. Oh my god. I can't go back. Don't make me go back. Doctor, please, please don't make me go back.
DOCTOR: Donna. Oh, Donna Noble. I am so sorry. But we had the best of times.
DOCTOR: The best. Goodbye.
DONNA: No, no, no. Please. Please. No. No.
(The Doctor mind melds with Donna and takes her memories away.)
(Donna passes out.)
DOCTOR: She took my mind into her own head. But that's a Time Lord consciousness. All that knowledge, it was killing her.
WILF: But she'll get better now?
DOCTOR: I had to wipe her mind completely. Every trace of me, or the Tardis, anything we did together, anywhere we went, had to go.
WILF: All those wonderful things she did.
DOCTOR: I know. But that version of Donna is dead. Because if she remembers, just for a second, she'll burn up. You can never tell her. You can't mention me or any of it for the rest of her life.

So the Doctor-Donna couldn’t deal with having the Doctor’s mind in her brain.

But the human Doctor born out of meta-crisis earlier in the same episode never showed any kind of insanity till the end, and The Doctor also wasn't worried about that. He was talking about spending his life with Rose.

The meta-crisis Doctor had human brain, and he possessed a Time Lord consciousness with the entire knowledge of The Doctor.

Why wasn't he affected in the same, or any, way?

My mistake that I didn't realize meta-crisis Doctor was a hybrid, but Doctor-Donna was also a hybrid. In the episode The End of Time, The Master transformed all humans into himself, but Doctor-Donna wasn't affected.

Update 2:
To prove that Donna was really a hybrid, here's quote from Journey's End:

DALEKS: Exterminate. Exterminate. Exterminate.
(Donna works more controls on the panel.)
DALEK: Weapons non-functional.
DONNA: Phwor. Macrotransmission of a K-filter wavelength blocking Dalek weaponry in a self-replicating energy blindfold matrix.
DOCTOR: How did you work that out? You're
NEW DOCTOR: Time Lord. Part Time Lord.
DONNA: Part human. Oh, yes. That was a two-way biological metacrisis. Half Doctor, half Donna.
DOCTOR: The Doctor Donna. Just like the Ood said, remember? They saw it coming. The Doctor Donna.

  • The doctor added a defense mechanism to Donna. He says so in end of time part 2
    – user16696
    Jan 30, 2015 at 20:24
  • @cde Don't take words literally. By defense mechanism, he meant meta-crisis.
    – user931
    Jan 30, 2015 at 21:01
  • 2
    It was a two-way metacrisis, as Donna stated, but that doesn't mean 50% transfer. I think it's more likely that Crisis-Ten was moved a small way towards human (let's say 20%), which made him lonesome-hearted and incapable of regenerating. Likewise, Donna was moved 20% towards Timelord, which was probably enough to help her in The End of Time, but not enough to allow her to safely store all the information that she'd obtained from the Doctor. I don't have any quotes to back this up, unfortunately; it's just my interpretation. I won't put it as an answer unless you think it fits.
    – Liesmith
    Jan 30, 2015 at 22:58
  • @Liesmith I think, half means 50%.
    – user931
    Jan 31, 2015 at 3:03
  • 3
    @SS Don't take words literally. By half, he means partially.
    – Liesmith
    Jan 31, 2015 at 7:19

4 Answers 4


DONNA: What, like you're human?
NEW DOCTOR: Oh, that's disgusting.
DONNA: Stop it.
NEW DOCTOR: No, wait. I'm part Time Lord, part human. Well, isn't that wizard? 

The meta crisis doctor is a hybrid, a unique one if we take him at his word.

Donna only received the doctors entire memories and knowledge, no other changes. That's what makes the two different, and why Donna started having seizures while 10.2 didn't.

There is more expository bits in the rest of the same episode transcript.

  • But, Doctor-Donna was also part Time Lord as displayed in End of Time..
    – user931
    Jan 30, 2015 at 19:27
  • @SS that's a defense mechanism the doctor put in place.
    – user16696
    Jan 30, 2015 at 20:25
  • Back this up with quotes if you think so.
    – user931
    Jan 30, 2015 at 21:01
  • 1
    Lack of information about Donna proves nothing. I am quoting Donna again: That was a two-way biological metacrisis.
    – user931
    Jan 30, 2015 at 21:31
  • 1
    A hybrid, eh....
    – Adamant
    Jan 15, 2016 at 17:55

Genetically, the meta-crisis Doctor is still half Time-Lord. He had many human characteristics (one heart, not regenerations) but he was not a human being like Donna was:

Soon after his "birth", he says:

NEW DOCTOR: No, wait. I'm part Time Lord, part human.

Later, in Pete's dimension:

NEW DOCTOR: I'm part human. Specifically, the aging part. I'll grow old and never regenerate

Though he has some human traits, he is not human; he is a Time-Lord/human hybrid. He was formed from Ten's DNA mixed in with bits of Donna's DNA, giving him part of her personality, but that didn't make him human.

Thus, it's not really valid to compare him to Donna and expect the two of them to experience the same effects; obviously, whatever makes Gallifreyan brains different from human brains to let them contain all that knowledge is present in the meta-crisis Doctor's brain.

  • Genetically, the meta-crisis Doctor is still half Time-Lord. ~> Citation? Tell me one Gallifreyan characteristic he possessed.
    – user931
    Jan 30, 2015 at 11:35
  • Also, comparing River Song would be nuts. She didn't have the entire knowledge of The Doctor.
    – user931
    Jan 30, 2015 at 11:36
  • Characteristics aren't important. Time Lords and humans have no genetic relation, they just happen to look (almost) the same. He may look entirely human but his genetics may be entirely different.
    – George T
    Jan 30, 2015 at 12:00
  • @SS the citations are the times he said so himself, which I've added in.
    – KutuluMike
    Jan 30, 2015 at 15:53
  • But, Doctor-Donna was also part Time Lord as displayed in End of Time..
    – user931
    Jan 30, 2015 at 19:27

Although the metacrisis was "two-way", the metacrisis Doctor was able to grow from The Doctor's severed hand due to the fact that the Tenth Doctor had channelled the best part of a full regeneration's worth of regeneration energy into it. The metacrisis affected both the hand and Donna, but the regeneration energy only acted on the hand. Donna underwent no physical change. This is stated by Donna:

DONNA: "He poured all his regeneration energy into his spare hand. I touched the hand, and he grew out of that but that fed back into me. But, it just stayed dormant in my head till the synapses got that little extra spark, kicking them into life. Thank you, Davros! Part human, part Time Lord. And I got the best bit of the Doctor. I got his mind".

This is evidently why Donna's change was not sustainable - she didn't have the physical mind to hold the Doctor's intellect.

As the metacrisis Doctor's physical appearance seemed entirely based on The Doctor's, the only physical aspects of Donna that he inherited being a single heart and an inability to regenerate, it seems reasonable to assume that he did have the physical capacity to hold The Doctor's intellect without 'burning up'. His physiology and intellectual capacity grew simultaneously, so one could not have exceeded the other anyway. Donna's quote that she "got his mind" also suggests that the exchange was random, and the metacrisis Doctor didn't have to inherit as much from Donna, which makes sense given that the hand contained The Doctor's full 'DNA' and the regeneration energy needed to form. It may only have been missing tiny component parts from Donna.

  • To be fair I don't think even a natural Gallifreyan can regenerate. It strikes me as a technology merged into their body. Take that wisp of multidimensional energy and apply it to a machine and you have a TARDIS or a Moment. Apply it to Gallifreyan and you have a timelord that can sense time and space and have their memories backed up and remake every atom of their body. Jul 23, 2021 at 14:40

In the Trenzalore episode the Doctor clearly states that a body is something a time lord possesses, and clearly not identical to the timelord itself.

Clara: What's that?
The Doctor: What were you expecting, a body?Bodies are boring. I've had loads of them. That's not what my tomb is for.

I think the metacrysis Doctor is a hybrid of the body the Doctor possesses at that time and Donna Noble. Of course that body contains as much of the Doctor as possible, but not him. Not fully.

Also Donna Noble after the metacrysis is a hybrid of Donna Noble and the Doctor (and not only his body) so I guess she is way more unstable than the other being.

  • Most of the answer is somewhat agreeable, but that finally part is completely wrong. We see 10-2 several times after his creation. The last time we see him is on the beach with Rose.
    – Omegacron
    Jan 30, 2015 at 15:18
  • I assume you are right and edit my answer accordingly.
    – mg30rg
    Jan 30, 2015 at 15:25
  • That quote is out of context... he was talking about a time travelers remains. If you want a better quote, the doctors daughter points out the difference between Gallifreyan and time lord. A shared code, knowledge, not just two hearts.
    – user16696
    Jan 30, 2015 at 18:13

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