ratchet, post-predacons-rising, finding out that optimus’s spark was reincarnated as one of the other new cybertronian lives

ratchet actually finding him and being hit with this confusing tsunami of joy and grief, relief at being reunited with his partner conflicting with the fact that he knows this is very much not his optimus

ratchet not being able to reconcile all these feelings with each other in the least, just feeling compelled to take care of him

papa ratchet raising baby orion 2.0 like he was their kid, his grief gradually dissolving as time goes on and he bonds with this new sparkling and watches him learn things and grow into his own person