I'm pretty sure a Ghost can't become someone else's Ghost. Sagira doesn't count because she didn't 'become' our Ghost. It was still our literal ghost, just with a new personality, but the physical Ghost wasn't a 'new Ghost'. If you read some of the D1 grimoire, there are a lot of sad stories of Ghosts who go basically go mad or helpless as they endlessly search, never finding their Guardian. Or, they had, but they died in a way that they couldn't be saved. So they wandered, never finding purpose. -- Clearly, while the Light is a'vauge and overarching power, it is also unique to every Guardian on some certain degree. That is why when you revive someone you activate [u]their[/u] Ghost, and not simply raise them yourself. That is why our Ghost couldn't save Cayde. That is why Eris couldn't become a Guardian anymore, as she had no Ghost, and couldn't simply pick up a new one even if she wanted to. -- Also... Ghosts can choose not to revive their Guardian if they believe, to a great enough degree, the Guardian has simply gone too mad or too far to the point they can't be saved. I don't remember which card it is, but one Ghost tells a story of a Guardian who constantly goes on mad adventures, fighting rusted machinery as if it was a monster, or tries to subvert the advance of an army that is really just the rain. All insane rambling and dementia. It came to the point that the Guardian 'figured out' the Traveler was the source of all of these 'monsters' and set out to slay it (or, at least, proclaimed the traveler should be rejected) Soon enough, the Guardian kills himself yet again trying to 'fight' these insane machinations, and the Ghost simply never revives him. He knew it was better that way. -- A slightly different story, but depressing, was the Ghost of one of the Guardians who believed 'death could grant knowledge'. I know there is a name for that type of Guardian... but I don't remember it. The Ghost simply told the story of the process of watching him jump off a cliff, smash into the ground in a splat of red fluid and bones, and then would be resurrected to simply do it again and again and again and again... never finding out anything, never replying any differently. Just goes to show some of the distasteful things a Ghost faciliates that they, otherwise, would simply wish would stop. Seeing the Guardian constantly, and willing fully, fall into goey pieces on the ground on impact over and over would certainly make anyone insane (or extremely disguested) after a long enough time of watching...

I highly doubt that our Ghost belonged to Saint-14, and is it really so hard to believe that our Ghost cares about us? His entire purpose in life is to find a host to fight for the Traveler, considering how long he'd been searching and everything we've done as a Guardian up to this point I think it's safe to say that our Ghost considers us as it's best friend (perhaps even family) by now

He met Saint, he wasn't his.

Out ghost was saint-14’s friend, not ghost.

But when was my ghost Saint-14s? Pretty sure my ghost was created for me. Wasn't that the line in the beginning of D1?

Wtf do you mean our ghost was Saints ghost