Well, not in a strictly reproductive sense, even if that's generally what compatibility's referring to-- that's more difficult to manage, you find problems with that even in similar species...

[--wait, no, he was using that as a pickup line and this is utterly counterproductive. He stops himself there, exhales a slow breath, and lets his eyes slide shut as he focuses on the feeling of fingers in his hair. That's... really nice. Nicer than he remembered it being.

Ryan finally bridges what little space is left between them to lean right against Garrus, one hand settling tentatively on his waist.]

...compatible enough. Of course we'd have to test to be sure, though.