The furthest you can currently go with Riley is making out. Only a few characters in the game are willing to hook up after knowing Connor so briefly, but as the game progresses more and more guys will be open to it.
wow thank you, i'm looking forward to that
Who can I hook up with
(SPOILERS for anyone reading this who wants to be surprised)
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In the current release, you can hook up with Leo, Marco, and Julian. There will be some more hookups added in the next update.
(END SPOILERS)