In the bloom in Small Nihilesh the NPC Aen-Tozon can be found.
He wants to feed on the mind of a party member. You can pick any party member that likes you except Rhin.
Let him feed, speak to Rhin about him to finally find out how she ended up in this world.
To open a portal to Rhin's home he has to feed again but he doesn't want a party member this time.
Go to Wondor who is standing right next to you and pretend to be Adahn when he mistakes you for him. Ask him to do you a favor and let Aen-Tozon feed on him. Speak with Aen-Tozen again and he will feed and open the portal.
Encourage Rhin to go through and you will get this trophy.