He was an autobot leader at a time before Sentinel Prime, Alpha Trion mentored him, hoping he'd become a proper Prime, but Pion failed to develop a connection to the Matrix and wasn't able to access it's power.
And he had heard from us already! Excellent, sometimes I think nobody reads us :(
But it's good to know we've reached people.
We have most stuff planned, there are mostly detailed storyarcs for season 2.5 and 4. But stories like this one set in the far future was a story Simon had already planned and kinda fit.