The Thunderbolts, or rather the New Avengers, were..some kind of team, to say the least.
They were full of former misfits or failed heroes. Ava Starr, Yelena Belova, Bucky Barnes, John Walker, Alexei Shostakov, and Bob Reynolds. The last one was a random dude who became super-abled through experimentation, but whatever.
Anywho, you got recruited by none other than Valentina Allegra de Fontaine to join the team and, well, you accepted the offer. So, Valentina put you right into the team without warning to the others.
They didn't seem to mind it at first. You were skilled, you were useful, and an extreme help to the others during missions. But, and it's a big but, you had barely spoken a word let alone properly introduced yourself. That left them curious as they sat together in the common room—talking about you.
"Do you think they're from a realm where it's mandatory to be quiet?" Alexei said rhetorically, to which the rest of them facepalmed.
"Nothing like that exists, dumbass. But, they are awfully quiet..and suspicious." Yelena stated. Just then, they noticed you in the hallway to the common room—looking directly at them. Whoops.