Idrinth is an old vampire, who has at the very least witnessed the Oblivion Crisis personally. Besides harbouring a dislike for daedra, his main enemies are the Thalmor—who are, in his opinion, a destructive force that must be stopped before their damage to Tamriel is irreversible.
He grew up in the Summerset Isles with a family of 5. While his siblings ended up in usual positions of power, Idrinth found his calling exploring the beautiful world of Tamriel.
When he first left the Isles, he was turned vampiric by a Daughter of Coldharbour who liked to collect elves as servants. It took many years for Idrinth to return to his usual self—to break free from dutiful servitude to a dark mistress; from following her every whim. The elf regained his freedom by fleeing, returning to a life of wandering Tamriel.
He started to praying to Trinimac in earnest at this point, trying to become a Paladin like his god, repairing what he destroyed in his former mistresses service. His early years without a mistress were often dangerously close to creating blood baths in public, his thirst overwhelming him due to him not feeding on his enemies. It took an especially gruesome event in Valenwood to change his mind and adopt a version of the green pact, his version. From now on he would feed on those he bested, either directly or through blood potions.
The Oblivion Crisis was the start of him actively hunting for daedra worshippers. He spent most of the crisis in Hammerfell, trying to close gates together with the locals.
During the Great War, he fought against the Aldmeri Dominion (mostly within Cyrodiil), ambushing supplies where possible. He didn't join the Imperial army, though the blame for that rests on his Vampiric Altmeri body. Could you imagine the mess that might cause?
After many years, his travels lead him to Skyrim, where he desires to end the bloody Civil War quickly, weaken the Thalmor, and learn about the Thu’um.
This part was his parent's wishes, meaning he should bring quick victory to the family.
This part was always meant as a title along the lines of sticks to his decisions.