Oghren's Old Flame is Oghren's companion quest.
Walkthrough
Talk to Oghren until you can talk about Felsi, this begins the quest. Travel to the Spoiled Princess at Lake Calenhad Docks with Oghren in the party.
Then, talk to Felsi yourself first and pick up some hints on how to help Oghren later. You can either help him with hints, or sabotage his efforts with insults. Then talk to Oghren, who will talk to Felsi.
Any of the following will result in Felsi telling Oghren to come back and see her sometime:
- Tell her Oghren took on an army of golems, then tell Oghren to tell her it's fate, then tell Oghren to tell her he's been thinking of her.
- Tell her Oghren took on an army of golems, then tell Oghren to tell her it's fate, ask Felsi if she hasn't missed Oghren, then say anything besides telling Oghren that you have to go.
- Just watch the conversation, then tell Oghren to tell her it's fate, then tell Oghren to tell her he's been thinking of her, then say anything besides telling Oghren that you have to go.
Results
Following one of the aforementioned conversation choices you receive 250 XP. Any other conversation choice results in no XP.
If you talk to Oghren after and Felsi didn't tell him to come back sometime and you tell him "Not very surprising" then 
Oghren disapproves (-3). Otherwise there is no approval change.
Epilogue
Depending on what happens when talking with Felsi and your treatment of Oghren afterwards the Epilogue will change for him accordingly.
- If Oghren is successful with Felsi he will find her again and presumably marry her and have a child (which he names after the Warden). He will also become a Dwarven General in the human armies.
- If Oghren fails at his attempt but is cheered up by the Warden later on he becomes the first Dwarven General in the human armies, attributing it to "the best friend he ever had".
- If Oghren fails at his attempts and is treated badly by the Warden afterwards, he will become a drunkard and a public menace.
Bugs
- If you leave the Spoiled Princess and then talk to Oghren and tell him to "Go get her" you end up in the middle of Lake Calenhad. Although you are free to roam around in the lake and can get into the stone structure on the shore you find yourself quite stuck. To get out head towards the docks and talk to the boat man to reset yourself into the playing world again.
- Oddly, if you walk toward the rocks at the edge of the lake at the right angle, your selected character will somehow end up at the bottom of the lake. You can of course walk the entire party to the bottom of the lake in this manner, and some parts of the shore will be permeable—you can walk under the shore. Unfortunately, it's not possible to talk to the boat man from here.
- If ever, you do get stuck at the bottom of the lake - there is a way to be able to get out again. On the second slope/crease from the boat man - just before the rock formation (if you look up) you can 'climb' the slope. It's pretty easy as long as you keep moving upwards. As for any slope, your character might fall from the slope back towards the bottom of the lake - if this happens just try to climb again- moving at the right angle. Try to see what a person would do when mountain climbing.
- Once you've gotten back to the shore- and move onwards you'll find yourself stuck. Just use the mouse to target your character anywhere on the island and the character would move there. Afterwards - talk to the boat man and your party will spawn at your back.
- You can enter the Spoiled Princess again and talk to Felsi - this will start with Oghren talking to her in continuation to the Warden's "Go get her".-
If Shale is in your party (and Oghren is absent) the conversation between Felsi and Oghren will take place between Felsi and Shale. Oghren's voice will be heard, but all camera cuts will swing to Shale standing in the lobby of the Spoiled Princess.