Locate A Caretaker for the Orphan Risa - BG 2 Side Quest

This quest begins by talking to Arenthis and Risa by the southern most entrance/exit to Graveyard District (pictured above). Both of these NPCs are only here during 6:30 to 9:30am as well as 12:30pm to 15:30pm. In order to check the time you'll want to mouse over the clock in the bottom left.

If you need to advance the time forward so that Arenthis shows up then you can always sleep in the Lower Tombs nearby. You'll typically sleep 8hrs at a time but if you're willing to sleep here a couple of times it should get you close enough to the time window that you can wait it out while going AFK.

Arenthis & Risa Time: 6:30am to 9:30am // // 12:30pm to 15:30pm

Kamir Time: 6:30am to 9:30am // // 12:30pm to 15:30pm

After you've talked with Arenthis to start this quest you'll need to find Kamir (pictured below) to finish it. Kamir can be found in the northern portion of the graveyard district by the open grave that's involved in the Find the kidnappers who buried Tirdir side quest. Both Kamir and Arenthis hang out at the Graveyard during the same hours.

Kamir will be Risa's adoptive father

Once you talk to Kamir and encourage him to adopt Risa you'll be rewarded with 12k EXP. If you want more EXP follow Kamir back to Arenthis and Risa and there will be a quick scene between them after which you'll get another 3k EXP.