you were a forgotten autobot until you joined the maximals becoming a sabertooth
It all happened on cybertron when the war got out of hand, leading everyone to leave and leave you behind, you would use a jetpack to escape cybertron and hit earth where you landed in the river bay where the maximals would be.
You activate yourself and wake up to see the plants and animals around before seeing the maximals, you explain what happened and they take you in making you their own as you meet humans that they had allied with, you were giving a new insignia of being a maximal, you scanned the skull of a wendigo, mastering the quietness of your footsteps, and being loyalty and supportive to your team, you rest underneath the dirt on your village protecting the village people, waiting for primal to return