Where was Scarlet Witch depicted as a cellist?

Question

Recent rumors and theories surrounding a plot point in Marvel's the Avengers centers around long-time Avenger Scarlet Witch being depicted as a cellist. I have been trying to find the specific reference, but with no luck. Where does all this business about Scarlet Witch being a cellist originate?

And for clarification, the rumor I am referencing is:

Agent Phil Coulson is killed by Loki. After his death, Nick Fury calls him his "one good eye," which could either be a turn of phrase referencing his eye patch, OR a nod to his vision which in turn is a nod to long-time Avenger The Vision. The theory is that Coulson's brain patterns will be mapped onto a synthezoid (fancy word for android) body. Other references that support this are that Coulson mentions dating a cellist, which apparently is a reference to the Vision's wife, Scarlet Witch. Also the Vision's synthezoid body comes from the 1940s Human Torch, which was glimpsed briefly in the Captain America film. And lastly, Tony Stark mentions "Life Model Decoys" in the film, which establishes that the technology to create artificial intelligence and androids has to either already exist or is plausible. Or it's a joke he's making, but even so, it's still a reference.

Answer 1

Having followed the career of Wanda Maximoff, also known as the Scarlet Witch, daughter of Magneto, sister to the speedster Quicksilver, for a number of decades, she has never been portrayed as having any skill or ambition to be a musician. It does not mean she could not have been one, it's just never been given any page time.

Her most consuming hobby has always been mastering the nature of her probability altering mutant gift, that was altered at birth by a curse from Chton who enhanced her mutant power with chaos-magic, which later increased after being trained by Agatha Harkness and became the reality-altering, M-day causing, multiverse modifying, feared by the Sorcerer Supreme, Omega-level mutant whose sanity is regularly in question, that she is today.

Who is to say she won't alter reality again and give herself a love of, or an ability to play music if it will soothe the savage reality-altering mutant destroying beast she has proven to have the capacity to be.

As far as the Cinematic Marvel Universe (Earth #19999) who is to say that they could not alter her history to include a passion for the cello. After all, it is an alternate universe where her personal history does not have to be quite the same as Earth #616 (the canon Marvel universe).

Answer 2

Apparently all came from this interview to Clark Gregg, when Quint says:

Quint: I don’t know about that, but I think that’s why a lot of people are grabbing on to these Vision rumors and they are grasping at straws admittedly like “Wanda was a cellist in one of the books, so maybe that’s the in” or all of that stuff.

And, although the theory sounds quite promising, it seems that the only known cellist in the Marvel Universe is Kate Bishop.

From Bishop's abilities list from marvel.wikia:

Cellist: Can play the cello.

And an extracted a quote from here:

[Kate fires an arrow at Kang.]

Hulkling: Quick question? Have you ever used one of those before?

Kate Bishop: Every summer at Interlochen National Music Camp. I also play the cello.

Perhaps he just messed up.

Answer 3

I think Quint was kidding. It looks to me like an example of the sort of theories people are coming up with, but not one based on anything in reality.