(Note: no particular timeline. No pairings. No own anything Trollhunters. Just a little speculation on my part how it might have happened. Rated T for battle scenes, though no graphically depicted gore.)

"Blinky, can I ask you something?"

Blinky turned from the shelf he'd been reorganizing, making space for a few new volumes, at Jim's question. The teen, sans the Trollhunter armor, hadn't been expected but nevertheless was welcomed with a smile.

"You know you can ask me anything, Master Jim." The Troll gestured to a pair of chairs, and Jim sat down. He seemed...nervous, Blinky thought. For a few moments after Blinky sat down as will they were both silent, them he decided perhaps a little prompting was in order. "Is this something you're uncomfortable asking me?" Jim gave a short laugh.

"Just not sure whether it's something too difficult to answer."

"I'm thinking that by 'difficult' you're not meaning I might not know the answer."

"Yeah. And if it's too personal, or painful, or whatever, then it's fine."

"Very well, I'll keep that in mind, but I cannot say whether it is it not until you ask." Jim took a deep breath in, then let it out slowly and asked.

"You and Aaarrrggghh are close friends, and I've noticed that he is hardly away from you. I also remember that he used to be a Gumm-Gumm." Blinky slowly nodded, getting the idea where this question was going.

"All true, the latter sadly." He leaned back a bit, getting comfortable for what was going to be a long story. "You want to know how he came to our side of the war, and we met?" Jim nodded.

"I - don't think I could ask Aaarrrggghh!; it... might be painful for him."

"Quite likely so. And aside from him, I am the only one who knows all the details." Blinky took a moment to gather thoughts. "Much of what I will tell you is my own firsthand experience, much of the rest what Aaarrrggghh! told me later. Only a little bit is conjecture on my part or gleaned through deductive reasoning. And only a small handful of Trolls alive today know even the barest fragment of what happened those centuries ago, before the fateful Battle of Killahead Bridge..."