D&D DM question

i'm currently DMing a campain for one of my vetrain players. he's trying to become a chosen of silvanus, (forgotten Realms) currently he needs the heart of one of each cromatic dragon, i need ideas his quest though. he's a 23lvl druid, he has a small party or like 10lvl players, the campain is basically just for him. i have a great idea for the ending but i need some ideas for the middle.

Make a scenerio that he has to team up with a wraith or a illithid. Also, make him fight a tarrask. Is his character sexually active? There are countless possibilities if he is.