What connection did the Doctor realize following Missy's offer in Death in Heaven?

Question

In Death in Heaven, when Missy says:

Every battle, every war, every invasion. From now on, you decide the outcome. What's the matter, Mister President? Don't you trust yourself?

Then The Doctor starts thinking of words he said or heard before and realizes the connection:

DOCTOR [memory]: Tell me. Am I a good man?

DANNY [memory]: (saluting) Sir!

RUSTY [memory]: I see into your soul, Doctor. I see hatred.

DOCTOR [memory]: (to Robin Hood) I'm not a hero.

DALEK [memory]: You are a good Dalek.

DOCTOR: Thank you. Thank you so much.

And he realizes:

DOCTOR: I really didn't know. I wasn't sure. You lose sight sometimes. Thank you! I am not a good man! I am not a bad man. I am not a hero. And I'm definitely not a president. And no, I'm not an officer. Do you know what I am? I am an idiot, with a box and a screwdriver. Just passing through, helping out, learning. I don't need an army. I never have, because I've got them. Always them. Because love, it's not an emotion. Love is a promise.

Did he realize that the connection was that he will always be the Doctor and save the galaxy for all of his live but, what was the connection he realizes?

Answer 1

Just prior to this scene, Missy gives The Doctor a control bracelet for the Cybermen she has created ("A birthday gift", she says). Basically, she offers him her army. Then we have the scene you describe but it's critical towards the end that

1. Cyberman Danny puts his arm around Clara when the Doctor talks about "love is a promise"
2. He throws the bracelet to Danny

The connection he makes is not about him, it's about Danny. As he says, he doesn't need an army. Danny putting his arm around Clara confirmed that Danny was in control of himself. Throwing the bracelet to Danny lets Danny command all the Cybermen to fly into the sky and self-destruct.

If you want to draw a conclusion about The Doctor, it seems that Missy was tempting him with power to push him to let that power go to his head (Missy says "I want my friend back"). The Doctor was clearly troubled that he wasn't a good man and would indeed fall into the trap. His realization is that he is neither good nor bad (nor does he need power). He's simply The Doctor. Thus giving the power to Danny resolves the conflict within him.

Answer 2

If you watch series 8 carefully, there is a clear story arc. The story arc is the Doctor's character development. The Doctor's appearance is old: remember what Madame Vastra said, that the Doctor has lifted his veil and revealed himself, changing from young to old. Parallel to that, his character is more open-book type, unlike his predecessor (the 11th Doctor) who always hid his feelings and made himself a closed book.

The 12th is beginning to question himself in the series (and in series 9 too):

• Starting in Deep Breath, in his confrontation with the mechanic robot.
• Then in Into the Dalek, where he questions Clara "Am I a good man?", to realising that he is a "Good Dalek" and full of hatred.
• In Robot of Sherwood, he states that he is not a hero to Robin Hood, indicating that he is still questioning his identity.
• In Listen, we explore the Doctor's fear and how he overcomes it. We can also deduce from this episode that the Doctor is always in fear because he always runs and is brave.
• In Time Heist, the Doctor hates "the architect" upon realising his identity. He is quite hating himself, though I'm not really sure how to elaborate this one.
• In The Caretaker, the Doctor expresses his care for his companions, shown by his early disapproval of Clara's dating Danny because he was a soldier. But then, as long as his companion is safe, he is okay with it.
• In Kill the Moon and Mummy on the Orient Express, I'm not really sure about it, so I will skip this one, but I think the Doctor is dealing with his attitude and relationship with Clara.
• Contrary to Kill the Moon (maybe because of his tense with Clara in Kill the Moon), In the Forest of the Night shows the Doctor trying to help to save the Earth, and not letting humanity act alone (this development leads to the part of his speech "passing through, helping out").
• In the series finale, we see the Doctor is helping Clara to find Danny in "hell" even though that might break the laws of time and also even though he has been betrayed by Clara. That is because he is trying to be the Doctor, always helping no matter what. And in the end, he is confronted by Missy, who wants to help him save the universe. The Doctor, who always wants to save the universe, is faced with this moral act of using the cyber-bracelet.

He is remembering his promise of the Doctor: "never be cruel, never be cowardly". Using an army to defeat monsters is a cruel and cowardly thing, one thing that the Doctor doesn't want to be. So be it, he is realising his own character: full of hatred, hates soldiers, not a hero, never uses weapon, never be cruel, never be cowardly, always cares for people, always helping out with only a box and a screwdriver.

Here's where I found this, in a comment on this Youtube video: