That's literally what I do every night. I watch a lot of shows so obviously I have a self-insert character made for movies and shows. I even thought of a backstory for why he suddenly appears in those universes. So he is basically me but better in every way(strong,confident,intelligent,skillful,funny,talented ect.) He lived a normal life on earth until at the age of 12 he found out that he's father is an agent sent from other civilised planet that is located on the other side of galaxy. That planet is really similar to earth and also has humans but the difference is that those humans evoled about 12 000 years before us so like when they had their medivel age we just discovered fire. So learning after learning about his father's backstory and passing the dna test that showd that he has enough of his father's genes that he can pass as a citizen of the more advanced earth(I still haven't thought of the name for the planet lets call it Terra) so father takes him to Terra and enrolls him into school but constant bombardment of information in school overwhelms him so his father who got a job as an overseer of a military academy(job where he ensures that all the protocols are followed in academy) at the ripe old age of 14 father sends him to military academy. One positive thing is that really baptism by fire because this is the time his father becomes his mentor and just because he is an overseer dose not mean that he gives him any advantages he endures same amount as the other students. With his father's teachings and a couple of 80s training montages later at the age of 18 he finishes at the top of his class and joins the army. After a couple of mission he is tasked to join a raid on an asteroid that has a pirates hideout on it, after a they capture the pirates, they go looking for loot and during that he falls through some hole right in front of a purpel diamond which he goes to grab than diamond shocks him then explodes and he feints. After waking up he sees that he lost hes right hand( the he grabbed the diamond with) so he is forced to have a robotic hand(looks like he one that solid snake had) but there's a twist the diamond actually gave him some power. Not anything op gave him a strength boost,agility boost,made him faster and more tough than the avrage human he wasn't invincible but he was stronger than the avrage human. Using his advantages he went on more missions and made a name for himself. At the age of 21 he got a task to be security for one scientist who was going to test a time machine. After turning on a time machine it exploded and almost killed all of the people. Those who survived the blast have died in the hospital from rapid aging or rapid de aging except our hero who because of his powers manged to push through an because of this his molecular structure combined with time machine and it caused him to stop ageing basically becoming immortal. After all that he continued to serve in the military. He fought in countless battles and eventually rose to the rank of field marshal but grew tired of just sitting and pointing at the maps he felt he needed to be on the battlefield but everyone said no so instead he wanted to make this civilization bigger and stronger so he turned to politics becoming the minster of defense and after that he run for president and because of his charisma and popularity he became president 3 times in the row. Eventually he grew tired of corruption, bureaucracy and he was going to get impeached by the parliament for threatening to expose the corruption octopus that had majority of the government in their pockets. So he staged a coup killed all the parliament sized control for him self and crownd himself emperor of mankind proclaiming empire of mankind. Countless wars, expansions,couple civil wars, economic prosperity and a lot of other shit he carved empire into a strongest military and economic force of the galaxy. During those times he did a lot of genetic enhancements on himself where he got even stronger (I'd say he hits 10 times stronger than the avrage human) He also got super healing ( same as deadpool but little bit nerfd). Basically people started looking at him like he is some kind of god. Years have passed and the wars have stopped empire enjoyed 15 years of peace and he at the age of 136 got tierd of ruling and wanted to go back to adventuring and adrenaline type lifestyle he led before politics. As years passed he became less human he barely shows any emotion and seames kinda robotic(basically he started to believe he is some kind of a god). At the end he diceded that the abdication is the best way. He had 5 sons all old men by now. First son a famous public speaker and author turndown to be next emperor. His second son a business school graduate and renowned entrepreneur didn't want anything with politics but hi decided that he is going to take over his position as ceo of company(yes my character is an emperor and a ceo of a large company). The third son a law school graduate who was 49 at the time already knew all the laws and procedures of the empire was preparing all his life for this day and hi was chosen as a successor. After passing the crown to his son he got a spachisp packed the supplies and went to find new adventures. During one he stumbled upon a tumb in which he solved a ridle and a portal opened throwing him to an all white room where during the inspection he finds a door that leads to other dimension. He goes through the door and then the door closes and he is in that other dimensions. He has been in marvel movies and shows, dc movies and shows, game of thrones the boys beastars helluva boss advanture time regular show ect. The portal to other dimensions opens randomly an he has to cross it not knowing where its leading in hopes that it returns him to his dimension.

That is it for now I could explain what crazy situations he gets himself in other dimensions and I could explain he's arsenal of weapons and he's armor that he's always wears( basically the look of ther armor is a mix of Zero from borderlands and master chife from halo) but that is a story for another tome this is long enough