He just joins him and cuddles up to him, Cheavy wrapping an arm around him out of reflex. Maybe it was in front of several teammates and they didn't intend to do any PDA so it's the first time they're really publicly affectionate in any form, Cheavy's embarrassed and goes to move his arm away, only to realize he doesn't want to. Maybe he takes a look at Medic's pleading face and decides to bear it a little longer.