Well we already knew from the initial announcement about Theo joining the cast of "Divergent" that Veronica liked him as Four.
She was in LA recently attending the LA Times Festival of Books and a fan asked her about working with Theo. She sounded like she was pretty impressed with his audition.
Have a look at the video below to see for yourself what she says about it.
Now if only there was video of that audition *wishful thinking*
"He was defintely the right choice!" You heard the lady!
Source via DivergentFans