The Witcher 3: Wild Hunt [ACT 1 VELEN] *CARNAL KNOWLEDGE* A Favor for a Friend (VIDEO)
After the quest, A Towerfull of Mice, you are tasked with finding a merchant bringing supplies for Keira who has not shown up.
After finding the supplies it’s pretty clear they are not magic related and she invites you to have dinner with her. It’s not incredibly difficult to sleep with her at this point but you do have the option of just laying together and watch the stars. Either way your decision won’t prevent you from romancing anyone else.
At the end of the quest she whispers something in your ear and you pass out. When you awake alone the next morning it’s clear something is up and the quest Advancements in Learning becomes available.
GAMER TIP: It’s a short swim over to the Island where Advancements in Learning takes place so I highly recommend getting it out of the way early so you don't forget about it. You can also complete the quest Forefather’s Eve while you're there, before or afterward depending on whether or not you accepted the Pellar’s offer outside of Keira’s hut earlier in the game.