After my first death, I looked into what the Gatekeeper of Umbra does with the story of one's death, and found the following:

I am frequently asked about my relationship with the Gatekeeper of Umbra, and by extension, the purpose of the Gatekeeper. I admit, in my most prideful moments I cannot help but think of the Gatekeeper as an old friend that I have known since I was small. Someone I have shared countless stories with, and someone I have had deep and powerful conversation with. Ah, but I digress. You’re not here to listen to me blather on about the good old days. You want to know about the Gatekeeper.

The Gatekeepers are fascinating creatures, although I admit that I cannot confidently speak to Vigor myself. They exist as a nexus between worlds, giving us a second chance at life. Of course, the question of “why” presents itself, and, tragically, at this time the why of it is a mystery even to me. But we do know that they exist, and that they exact a toll when you pass through them. To the Gatekeper of Umbra, one presents a story. A story of life, or death, what one has seen, whatever comes to mind. This is what we offer the Gatekeeper of Umbra before awaiting our return to Evren.

I am frequently asked “what happens next”. What does the Gatekeeper do with this tale? Does it affect one’s return from the bridge? The simple answer I will give you is “the Gatekeeper listens, and does not judge”. No, what tale you give does not affect whether or not you return, nor the state of your return. The tale you give is simply a toll you pay. Of course, I would not grow lazy in the telling. Remember that this being does hold the power of your spirit in their hands, and in the incredibly slim chance that your tale is sufficiently lazy to offend them, you could simply fail to return to Evren. Be polite, and give them what they ask.

But what happens to the Tale once it is given, you then ask, yes? Why is the Gatekeeper amassing these stories in the first place? To this I answer, what does any storyteller do with the stories they collect? They keep them, remember them, and think on them. In many ways, the Gatekeeper of Umbra is the ultimate impartial narrator. They collect the stories of Evren, one by one amassing pieces of the greater tapestry that is our realm. Few would know as much as the Gatekeeper does of who we are, for, truly, it is they who see us at our best and worst. They hear the tales of our courage and cowardice. And this is enough.

-Excerpt of a lecture by Tanar Nataliya LeConte, Venerable Master with Accolades of the Invisible Arts