It leaves him wondering what they really were, but that's not the important thing.

He's been alone. Starved of contact and conversation and now he has things to do. A purpose, a plan, and Delta rewarding him so very sweetly for it. Isaac sinks into his hands all too willingly, making a faint noise in the back of his throat as he returns the kiss, reaches to return the favor.

Seems fair, right? Delta's making him feel good, and he knows he can do that.