"Mikhail is the oldest. They told us he was dead."
Illyana vaguely remembered that much from her childhood.
"Then you saved me from the tractor, and then left to go find better work."
Illyana didn't get closer to the man claiming to be her brother. Why would he make up a story about Illyana being the oldest? That part didn't make sense and she was too new to the ship and too inexperienced in SHIELD to think of alternate realities.
She was beginning to think, at the very least, he believed the story. Illyana pulled the hood of her jacket down a little lower with her free hand, worried how he might react if he got a better look.
She failed to mention the part where she was kidnapped by Nazis. One step at a time. They were still working on the base level of trust step.