Marsha is found to be '1000 years old'. Throughout the series, Marsha has flashbacks that show Marsha aging over time. During a period which is presumably before, during and shortly after the Mushroom War she is shown as a young girl. Later, during the time she is living unhappily in the Nightosphere, she appears to be a kid, but no longer a toddler. In the scenes where she is in Ooo she appears to be closer to her current age.
According toMarsha, Hunson is the one who gives Marsha Sparkles, her most loved plush toy. She looks a few years younger than her youngest appearance at age 5.
Marsh states that he is the son of a demon and the Demon Prince.
Where we see a universe where events transpired differently, and Marsha is never bitten, abut appears 14. She staes that her family (exept for Marceline was frozen for nearly a long tme. Also, in this episode, she refers to herself as "a half demon" instead of a demon and vampire.
- You created me, so don't you wanna see me?
- Daddy, why did you make me
- if you're not gonna take me to get a burger and shakey?"
- The first is that the War did occur a thousand years prior, and that the Ice King is older than the 600, closer to Marsha and Marceline's ages which, as stated, is at least 995-1000. Ice King is older than bothbecause when he finds them, they looks to be around 14 and 18 and he is the Ice King.
- Another possibility is that Marsha is lying about her age. As known, Masha fibs from time to time to make herself seem like she doesn't have quirks, such as keeping in the fact that she has autism. Thus, she may be lying about her age to make herself seem normal.
- Another possibility is that Marsha and Marceline's mother was a vampire, causing her to be born as a vampire. Given that there is no evidence that being bitten is what caused Marsha to become a vampire, this possibility is valid. If we assume that vampires age very slowly, she could still be "a child" by the time of the Mushroom War. It could be possible that the memory viewed of Marsha as a child shows her when she is 400 years old. If she currently appears to be 14 but is 995, some simple math shows that if we assume a linear change in what age she appears to be over time, when she is 400 she would appear to be about 7.2, which she indeed does. It is possible that being bitten did not turn her into a vampire, but simply granted her vampire powers. This means she could have been bitten at any time before she lived with wolves, but after her dad abandoned her. This possibility suggests that the mushroom war occurred 600 years ago.
- Because Marsha and Marceline's father was a demon and not a vampire, it's possible that her physical characteristics of grayish skin, pointed ears, fangs, immortality, and shape-shifting abilities are actually demonic, not vampiric. She appears to be as intensely demonic as her father so perhaps her mother was only a human and died long ago. The first time we see her with bite marks is when she's with wolves. If Ice King is about 1,000 and was only about 30 when the war began, then Marceline's age depends on whether or not demons age slowly (altering her age when she looked like a child during a war), how long her mother had been dead around the time, and whether or not she, Marceline and Ice King were witnessing the same war. There isn't evidence that she was aging slowly up until the time she was bitten so it's likely she was the age that she appeared to be. If the war that Ice King experienced as a human being is the same one that left Marsha and Marceline alone in the ruins of their home, then he would only be about 25-30 years older than them. When marsha was bitten, she could have been permanently frozen in her teens and remained that way for the next millennium.
- Marsha and Marceline's Father, Hunson Abedeer, is a demon, but not just a demon, the Lord of Evil. He rules the nightosphere, a hell-like place. He probably fell in love with a human and they had two children, Marsha and Marceline. Both were part demon, from their father, which gave them a vampiric look, including pointed ears, almost white skin, and fangs as a little girls. Marsha didn't have the bite marks that turned her into a vampire in that memory, showing that she probably wasn't a vampire when she was little, just part demon. She didn't float like Marsha does now, she hops from trees in a non-human like way, probably because of her demon side. Marsha grew up around the era of The Great Mushroom War, the war that caused the apocalypse, and her, Marceline and her father survived because of their magic powers, but her mother most likely died in the war because she was a human. Marsha does have some memory of her though. We think hr mother e is deceased because in the show, she is rarely mentioned and never seen, where as her father is mentioned and seen multiple times on the show. Marsha's memories of her mother seem to only be from when she was little, which fits because in "Enter Marsha's Mind" she is seen as a little girl playing with her sister in a burning ruins of a city, probably the aftermath of The Great Mushroom War, and her mother wouldn't have survived so she must have been even younger when her mother was alive. In "Memory of a Memory" it is shown that Marsha is very emotionally attached to a plush Rainicorn named "Sparkles (later named Lady Rainicorn)." She is seen playing with it as a little girl after the mushroom war, and and she states that Marceline, Sparkles and Hambo is her only friends, probably because almost nobody survived the mushroom war and it would take a long time for society to re-create. In another memory Marsha is seen to have grown up and appears a teenager and still doesn't have any bite marks, proving further that then she wasn't a vampire because vampires don't age. Since her father is an immortal demon but her mother was a human, she probably aged very slowly. In the memory her father abandoned. She wait for him all day and by the end, gets upset. This along with other things caused Marsha and her father's relationship to be strained for a long time. In her next memory Marsha and her wolf friends, are all together in a cave that would later become Marsha and Marceline's home. In this memory she does have bite marks, and from this memory on her physical appearance remains the same, so Marsha must have turned into a vampire between when her father abandoned herand when she lived with wolves. There are no clues that point to how she became a vampire though.
- One possibility as to how Marsha became a vampire is that she was bitten by Marceline so Marsha could be a vampire with her. Going along with the theory that she is half demon and half human, it's possible that aside from the physical appearance inherited from her father and perhaps some supernatural strength, she otherwise would've aged normally (or at least close to normal). This is supported by the similar backgrounds between the scene of her as a small child and the scene of her as a teenager. If this is true, then we can assume that some years after the scene where Marsha is abandoned by her dad, she was bitten and turned into a vampire. This would've stopped the aging process and place her at her current appearance of late teens to mid twenties. Since vampires (classically) only feed on victims and don't normally turn people into vampires, it is reasonable to assume that whoever turned her into a vampire intended to make her their companion. This is especially true if vampires in the Adventure Time universe don't need to drink blood to survive. Marceline also would've been an unlikely candidate to feed on, given her demonic appearance. This leads me to believe that it was the Vampire Prince who turned Marsha into a vampire, intending to get revenge. Marsha has yet to kill the Vampire Prince, so it follows that either immediately or some time after she was transformed by him, she hasn't killed him for reasons unknown. If we can assume that the memory of Marsha as a teenager happened over nine hundred years ago, and the scene with being beaten up the alpha wolf (Marsha is seen with bite marks, Ooo looks the same as it does in the show, etc.) then the gap between these scenes could be many centuries. This implies that aside from Marsha being bitten and turned a few years after the abandoning scene, the killing of the Vampire King could have happened at any point in that time span.