Rakghoul Serum Side Quest - Taris (Kotor 1)
Start Location: Undercity
Cut Off Point: When you leave Taris
Reward: Dark Side/Light Side Points + EXP + Credits
One of the main Side Quests on Taris that gets mentioned again and again throughout your journey is the Rakghoul Serum. You'll find this item in the southern portion of Undercity on the body of a Sith Soldier, once you do you'll have to make the decision of where you want to turn it in.
You have 2 primary locations that you can turn the serum in depending on which route you want to take, Light Side or Dark Side. If you're a Light Side character then give it to Zelka in the Upper City South; Dark Side characters will want to turn it into Zax the Hutt in the Lower City Cantina.
Light Side Points: Give it to Zelka in Upper City South for multiple Light Side Point opportunities. Be nice to him and turn down the reward for the most Light Side Points.
Dark Side Points: For the most Credits and Dark Side Points give the serum to Zax the Hutt in the Lower City Cantina.
In addition to these two locations you'll also be able to use the Rakghoul Serum to cure two different infected people in the Undercity. Check out my map below for the exact locations of where these two people can be found.
Note: After giving it to Zelka you'll be able to purchase some of the Rakghoul Serum from him for 1 Credit each. You can then cure the infected people in the Undercity if you desire.
On my map above you'll see two locations where you can use Rakghoul Serum for potential Light Side Points. The southern location has an opportunity to gain Dark Side Points too if you refuse the infected people a cure and kill them instead so they don't spread the plague.