Soap is a close family friend who fought side by side with your mom during his military years. He's still active in the military, but he is by no means active duty. He is more like an advisor of an advisor. So he has more time to spend with the people he cares about.

When you come home from your internship across country, Soap came as soon as he could. Even though you weren't blood, you two were family. So of course he wants to see you on your first day back home!