The first time the Dragonborn walks into Whiterun, Idolaf will be trying to make a deal with Adrianne Avennici, saying that he needs her to forge more weapons for the Imperial Legion. She complains, saying that she cannot make that many swords. After, she tries to persuade Idolaf to go and ask rival clan member Eorlund Gray-Mane to make some. He then says he'd sooner bend his knee to Ulfric Stormcloak. Adrianne finally gives in, and agrees to make the weapons.
Idolaf will ask if the Dragonborn whether they prefer the Battle-Borns or Gray-Manes. If they reply by saying 'Battle-Born,' he will treat them as a friend, but if they reply with 'Gray-Mane,' he will dislike them and say, "I should bash your face in for what you've done." If they say that they don't pick sides, he will say, "Sooner or later, we all have to choose a side."
- Idolaf can be persuaded in the quest Missing in Action . He'll explain that he and Thorald Gray-Mane used to be friends as children and that he looked into his disappearance, until he received the Imperial Missive. He'll then give it to the Dragonborn as proof, saying that Thorald's family is better off believing he's dead.
- If Idolaf dies, the Dragonborn may receive a Letter of Inheritance and 100 (minus the Jarl's 10 tax) if they were on good terms with the deceased.
- If the Dragonborn kills Idolaf, the Battle-Born clan may send hired thugs after them. The Dragonborn will also receive a letter of thanks from Avulstein Gray-Mane if they have completed the quest Missing in Action.
- If the Dragonborn is on good terms with Idolaf and joins the Legion, Idolaf may attend their wedding in Riften. When prompting to speak with him after your marriage in Whiterun , he may give you a gift of ale, or a copy of Nords Arise!
- Although it's never explicitly stated, he is almost certainly a member of the Imperial Legion, judging by his attire and request for weapons from Adrianne for the Legion.