Response for a Prompt found on tf_rare_pairings on LJ :Ironhide/Optimus: loyal til the end, and beyond
Warnings: character death
Ironhide found his spark yearning to follow his Leader's to the Well of All Sparks. Their sparks and destinies were bonded in a way that only a leader and his soldier can be. But he knew he couldn't do it. He had sworn loyalty to the Autobot cause.
Back in the past when he had decided to join the Autobots he had wanted to give Optimus his oath, but the Prime had always declined. He had always said that Ironhide's word was enough, though Ironhide persisted. In every battle, on every field he fought his hardest, wanting Optimus to acknowledge him, to show that his cannons was Prime's to command. After each battle, the moment reports was finished Ironhide would stop him and ask for time to give Prime his oath. One cycle Optimus agreed.
Ironhide felt his spark quiver in remembrance of the moment. A quiet room on the Ark, no Allspark present, but the oath would be valid either way. The ancient words still rang in his processor as if he had spoken them yesterday, and then the exposing of his spark, giving himself to his Leader; he had sworn back then to follow him till the end.
But Optimus was no mere Leader of the ancient times. He was supposed to take Ironhide's oath only, but he offered his own in return – the Oath of a leader to never leave anyone behind, to protect his people to the last charge of his spark.
And Optimus fullfiled that oath to the letter. He considered Sam his soldier, his friend, and his spark was extinguished protecting him. Knowing that Optimus would do the same for him and that he couldn't do anything to either help or stop the Prime hurt the weapon's specialist.
Now he watched the gray sparkless husk that belonged to Optimus, and steeled his spark to follow the Autobot cause even beyond Optimus' existence.
Back then, when they had exchanged oaths, Optimus had demanded from him to give his word that Ironhide would follow the Autobots and not Optimus, because he was only a Mech and he was fallible but the cause of protecting the weaker would last forever.
Ironhide had never told Optimus that since then Ironhide felt for Optimus loyalty much deeper than mere soldier would for his leader.
Now even though his spark wanted to follow Optimus along, the oath bound him to follow the Autobot cause. He was an Autobot soldier first and foremost.