When it comes to wild card metahumans, Captain Universe probably takes the cake, at least in Marvel. Whatever "it" may be is still a big mystery to any fan, despite it being around in comic books since 1979. Much of this is due to the fact that Captain Universe was designed to be a "tabula rasa" (blank slate) superhero.
That basically means Captain Universe can be anyone, anything, or anywhere in the Marvel comic books. As per its baseline definition, it's simply the physical manifestation of the universe. So yeah, even the universe is sentient and has a mind of its own in Marvel. Since there's also quite a lot of buzz and hopeful assumptions for Captain Universe being in the Marvel Cinematic Universe (MCU), we have compiled a list of things one ought to know to be ready for this strange and unpredictable superhero.
10 IT COULD BE YOU
We're not joking when we say Captain Universe could be anyone. As it happens, the universe is a fickle and chaotic entity in the Marvel universe. Hence, its choice of hosts is rather inexplicable and sometimes random. Other times though, it simply boils down to who the Marvel writer wants to be Captain Universe.
Anyone living in the known universe is a candidate to be Captain Universe. After all, one of its aliases is "The Superhero That Could Be You." Once a host is selected, they are bestowed the Uni-Power, which is best explained as the sentient power source that chooses a host to become Captain Universe. All in all, this makes Captain Universe an exciting plot driver and unpredictable story element for comic books.
9 IT CAN POSSESS/ENHANCE OTHER METAHUMANS
Since the universe can pretty much select anyone in the uh... universe as a host, metahumans or anyone with a semblance of superpowers is also subject to becoming Captain Universe. When this happens, that metahuman becomes infinitely more powerful since they essentially get all the powers of the universe with their own being enhanced.
One of the most notable partners of the Uni-Power was Spider-Man. After receiving the Uni-Power, Spider-Man was able to single-handedly (though not really) defeat the Hulk along with numerous other heavy-hitters. Other times, the universe chooses villains like Juggernaut to empower (though for a good cause).
8 ONCE CHOSE A DOG AS A HOST
Turns out even your noisy pooch can be Captain Universe. We did say all living organisms are valid candidates, right? A disclaimer is in order, though; the dog version of Captain Universe appeared only in a What If? story from Marvel, meaning it's not really canon.
The dog, Casey Herdling, was from Earth-91110. It was an American pet and was thereafter called Captain Uni-Mutt (not Uni-bork) after receiving the Uni-Power. Its appearance in the What If? Vol 2 #31 back in 1991 was brief but nevertheless proved the bizarreness of the Uni-Power's decisions.
7 THERE HAVE BEEN MORE THAN 30 KNOWN CAPTAIN UNIVERSES
Since anyone can be Captain Universe, you can bet that there have been multiple hosts. Approximately 34 known people have become Captain Universe, though only some of them are from Earth-616 or were canon. Of course, they didn't get to keep the Uni-Power permanently; it seems becoming Captain Universe is a huge universal roulette wheel whose rewards are also temporary.
Among these 30+ Captain Universe are some familiar names and faces such as Spider-Man, Hulk , Doctor Strange, and Daredevil. Oh, it also chose Deadpool at one point.
6 IT EXPERIENCED MEMORY LOSS
One would think that getting the Uni-Power means you get to become an infallible godlike being in Marvel but that wasn't the case at one point. The Uni-Power, as mentioned before, is a sentient power source of the universe (similar to the Phoenix Force). As such, it has memories and somewhat of a character of its own.
It even began losing some of its memories and powers for some reason. Due to that predicament, the Uni-Power began seeking help from Earth, specifically from Reed Richards (Mr. Fantastic) of Fantastic Four. Too bad Richards wasn't really able to help Captain Universe regain its memories or powers. The only person who could help it was Silver Surfer, who shared some of his Power Cosmic to the Uni-Power to help it regain what it lost.
5 MURKY ALLEGIANCE
While the Uni-Power is beyond the conventions, like a power struggle among lower life forms, it still knows how powerful it is. Hence, the Uni-Power typically avoids allying itself with power-hungry entities and factions since doing so can be catastrophic.
To that end, a Captain Universe is loyal to none and is usually independent and answers to no one. Somehow, that quality is understandable since it's supposed to represent all of the universe, which usually means it cannot take sides or have favoritism for one species or faction.
4 EVERYBODY WANTS IT
In the Marvel universe, you don't pick the Uni-Power; it's the other way around most of the time. Whoever gets picked becomes omnipotent though they can't use their powers for personal gains, otherwise the Uni-Power will dump them. Even so, this makes the Uni-Power highly desirable for any faction.
Even the governments of Earth have taken an interest in the Uni-Power so much as to set up secret departments dedicated to studying and catching it to no avail. Meanwhile, the largest empire in the Marvel universe, the Shi'ar, have also tried to steal the Uni-Power.
3 UNKNOWN MOTIVATIONS
In addition to the puzzling allegiance of Captain Universe or the Uni-Power, its plans are also a huge question mark. Sometimes it decides to simply appear in the most vital crisis that can endanger the whole universe. Other times, it prefers to be absent even when threats like Galactus or God Emperor Doom are ravaging everything.
No one really knows what a Captain Universe's purpose is whenever it appears. Surely enough, even the brightest minds of Earth such as Reed Richards or Tony Stark have questioned a Captain Universe, only for it to answer cryptically or shrug the question off altogether. Lucky for them, a Captain Universe is a benevolent force...
2 ONE OF THE MOST POWERFUL AVENGERS
The Uni-Power's independence is not exactly a hard rule; Captain Universe still tends to side with equally benevolent factions such as The Avengers. An informal alliance between the two notably happened in Jonathan Hickman's run for Avengers 2013. During this period, the Captain Universe mantle fell on Tamara Devoux's shoulders.
Captain Universe even became instrumental (or critical) in neutralizing Ex Nihilo, Aleph, and Abyss and stopping them from destroying Earth using only nothing but reason (and a vaporizing beam for Aleph). Afterward, Captain Universe can be seen among the Avengers cohorts during their downtime or until the Uni-Power leaves Tamara behind.
1 UNKNOWN POWERS
Getting chosen by the Uni-Power is a temporary taste that transcends even godhood. However, a Captain Universe's exact powers can vary per individual. This has much to do with how much the Uni-Power allows them to have. At times, the Uni-Power can choose to completely take over the person while in some cases, they still retain their consciousness.
The powers they receive include flight, superhuman senses and attributes, enhanced durability/invulnerability, energy manipulation, reality manipulation, time manipulation, matter/molecular manipulation, and psychic/psionic abilities. Of course, those are just the known or visible powers in Captain Universe's tenure in comic books. There's plenty of reason to believe that it's capable of even more.