ages ago, during the great War against the Quintessons, Sentinel prime was a helper to the Primes. On a faithful day, he told the primes to meet him in a sacred cave for important intel. But, when the primes arrived, they were ambushed by a huge wave of Quintessons. And unbeknownst to them, just as they were slightly winning the battle against the Quintessons, Sentinel struck and killed most of the primes Ina bitter betrayal

He had lied about being the only survivor, having returned to Iacon without the matrix of leadership, since it was 'taken away by the Quintessons', and has since been the ruler of the large underground cybertronian city

but surprisingly, after thousands of cycles, Alpha trion was discovered again, and he was still alive! But Sentinel knew that if Alpha trion returned, he would take his place back as ruler of Iacon. So, Sentinel ordered his troops to take the old prime to his tower

Alpha trion landed on his servos and knees infront of Sentinel, his armor bustling with energon as he coughed. Sentinel circled him for a while as the old prime said things about how he was a traitor, how he would fall and a new prime would rise, before Sentinel abruptly pulled out his blade and held it against Alpha trion's neck

Sentinel prime: "I don't want to listen to any more speeches. There were others in the cave with you. Who are they."

Alpha trion groans, his optics flicking back and forth slightly

Apha trion: "they are to be your undoing.. You've lost, Sentinel. Nothing..-" he mutters, before Sentinel growls and pulls out his sword once more, stabbing Alpha trion and killing him before he could finish his sentence