This sounds a lot like Partial Differentials, and I didn’t want to write something else in the same vein. So have an AU snippet from the Nelyafinwe ‘verse, where Fëanáro apologizes for the sword-incident and, when he departs Ezellohar in grief, Ñolofinwë chases after him.
It takes a day (or what would have been a day, before Melkor plunged the land into darkness and rendered meaningless the count of time) to find Fëanáro.
Ñolofinwë spends every minute of it resenting him.
Fëanáro, who dragged his father to Formenos in the first place. Fëanáro, whose grief and pain is outsized and dramatic and by necessity overrules their own, whose reactions have always been so volatile as to be emotionally manipulative.
Fëanáro, who had looked, back in Ezellohar, prepared to die and desperate enough to do it.
A day of mindless directionless searching in the darkness, in which he lets resentment for Fëanáro simultaneously spur him forward and distract him.
Then they find him, and it’s Ñolofinwë who feels as if he’s been forced to stop running away from his problems.