"It quickly escalated, consuming England and then Europe and eventually the entire world. No one was able to stop either side, and governments began to fall and soon... well soon the entire world became their battlefield."
"Where am I, why didn't I stop them?" I asked them horrified by what had told me. 
"Well... you died. Your father killed you when you and your friends tried to overthrown and retake Hogwarts."
At this point the room began to spin, I felt sick to the stomach. I had died? But I was still here.
"Calm down Hermes." Janus said steadying me. "It's the power of the watch, it allows the creation of paradoxes, you're here at the end of the world even though you should be dead." 
I barely took in the words he had said. "Here I think you need a rest." He told me helping me to my feet and out of the room. 
***
I woke up a few hours later, still in shock from everything that had happened.
"Ah you're up Hermes." the older Janus said as I walked into the room.
"What do I do now then?" I asked him not sure what to do with myself.
"Well you could stay here for a while, I can teach you a few things like how to use that watch." Janus said.
I nodded at this and accepted. I ended up staying for almost a year, learning different types of magic for Janus, and how to control the power of the watch. He even taught me how to "re-watch" my memories, its how Janus has been able to remember everything.
He told me that after using the watch for too long you start to forget things, I guess a side effect of prolonged use of the watch, or a curses I guess. Janus has kept all of his most important memories in a storage, and he taught me how to create my own, and I can re-watch, or even re-remember them whenever I want.
He even began to teach me some divination, I didn't even know this was a thing, they got rid of it at Hogwarts. I think I'm pretty good at it, I began to see things that were going to happen in a crystal ball/
***
Today is the day. I am leaving Janus and the end of the world. I've met many different versions of him now. Apparently he has been hiding from Death at the end of the world for decades now. But it is my time to go, I know what I need to do.
""Hermes listen to me, this is very dangerous! What you are trying to do, the future you are trying to bring about it could be even worse than this one!" Janus pleaded with me.
"Is there a possibility that it could make things better?" I asked him, having gone through this conversation many times before.
"Well yes it is, but you could stop yourself from being born! Changing the past at this magnitude could be disastrous!" Janus told me.
"But it could make things better... It's worth it, I just know it!" I said, determined not to be dissuaded.
Janus sighed, clearing know that he was defeated. "Alright then. Here take this." He handed me the crystal ball I had been using. "It might be helpful, and don't forget about your memory box, don't lose that, you could lose your entire identity!"
I nodded knowing how serious this was. I set the watch to when I needed to go. I knew where I needed to start, I had seen it in the crystal ball.
I closed my eyes, as the watch began to glow in my hands, I could feel the metal start to warm up, and a bright silvery light burnt through my closed eyelids.
Finally the glow subsided and I opened my eyes. I was standing in front of an old looking house. I knew where I was. This was my Dad's house, the one he grew up in. 
I knew I had come to the right time, as I saw a pair men in dark robes walking towards the door. However, a few feet away I saw two people hurrying to stop the men.
I sprung into action, I knew what I had to do, but it would be difficult. A few days ago I had seen my Grandma, my Dad's mother being killed when he was just a child.
It had to be that made this happen. I moved swiftly and with determination, pulling out the wand I had taken, which Janus had told me, was in fact Death's own wand.
I charmed a nearby tree, watching as it reached out and grabbed onto the wizard that hurried past it, retching them off of their feet, dangling them in the air.
The witch that was with him whipped around, sending a jet of red light towards me. I cursed, as I knew I was too weak at the time to win a duel against her, yet I just needed enough time... enough time for my Grandma could die.
Even writing this now my hands are shaking. Through my actions I took a life. I know it is for the greater good, but still...
***
(Y/n) stopped reading for a second. He didn't know how he felt. This girl, his apparent daughter, had caused his mother's death, had caused his fear of Dolohov, had caused so much pain in his life.
Yet she had saved him from an even worse fate. He just couldn't understand his feelings. He brushed it off for the moment, and returned to the diary, turning a few pages ahead as they were too damaged to read.
***
It's over. Grandma is dead, and the future is set on a better path. But my work is not done yet, not even close. I've been looking through the crystal ball more and more. I've seen that there are more things I need to do. But the first thing I need to do is find a place to live, and somewhere to get money.
I've traveled to Diagon Alley already, and while there were jobs here, Diagon Alley is just too far away from Hogwarts. I've decided to look into Hogsmead, that'll be close enough to the school that I'll be able to keep an eye on Dad. Hopefully there's something available there.
***
I've found out what I need to do, apparently Dad's going to get attacked by a werewolf at some point. I remember Dad telling something about a werewolf in his third year, so that's when I've traveled too. I ended up arriving just before Christmas, and I actually found a job.
It's nothing fancy, in fact its far from it, but a job is a job, and Aberforth, my boss, is even letting me stay in the bar, so that's that sorted as well.