Before getting trapped in the pool, Mermando resided in the Gulf of Mexico along with his friends, the mighty dolphins. One fateful day, he was swimming with the dolphins when he was ensnared in a net by an old sea captain and his shipmate.
The captain announced they would feast on his flesh and had a truck take him to the Bait Shop at Lake Gravity Falls. He managed to escape as the truck was parking and jumped into the lake. He tried swimming against the current and up a waterfall, but failed when a log crashed into his face, causing him to lose a front tooth in the process. He ended up flopping onto the ground, but luckily the local wildlife were kind (or hungry) enough that they kept licking him, keeping him hydrated. Unfortunately, the licks that were keeping him alive were also tickling him and as he squirmed with laughter, he stumbled into a water drain that led to the Gravity Falls Pool. For an undetermined amount of time, he was trapped there, hiding his secret from others and unable to get home, until he met Mabel.
On the hottest day of the summer, Mabel met Mermando at the town's public swimming pool's opening day. Mermando found her charming and forward and took a liking to her. After their first meeting, Mabel asks him out on a date, and that night she meets him at the pool. Mabel attempts to kiss him by puckering up, much to his confusion. Mabel agrees to help Mermando return to his family in the sea and sneaks into the pool again by taking the Mystery Cart there, where she loaded the back with the pool's cooler and filled it with water. Mermando gets in and hides, while Dipper attempts to get Mabel to return the cooler. With a little distraction, Mabel and Mermando make their escape to Lake Gravity Falls. Unfortunately, the cooler springs a leak, and Mermando, so close to the water, nearly suffocates to death. Mabel convinces Dipper to give Mermando "reverse CPR," which he reluctantly does.
Now safely returned to the water, Mermando thanks Mabel and Dipper for their help. While the parting is bittersweet, Mabel is glad he would be able to return to his family (and gives him the Pool's megaphone as well, to call out to his family). As a farewell gesture and an expression of his own feelings, he gives Mabel her first kiss.
Mermando is happily reunited with his family but continues to send Mabel many messages in bottles which end up at the pool.
He sends Mabel another bottled message in "Society of the Blind Eye." He mentions that he has been arranged to marry the Queen of the Manatees in order to prevent an undersea civil war. Judging from the photograph he sent, he is unhappy with the arrangement.
In "Weirdmageddon 3: Take Back The Falls," his name is seen written on a tree in the end credits.
Mermando is described as a mysterious loner, due to not wanting others to know of his nature as a merman, though he enjoys having fun with those who know of his true form. He is polite with an easy sense of humor, often making self-deprecating comments. He tends to be dramatic, often playing his guitar for effect. He is very close with his family and loves them very much, and he nears depression when separated from them. He tries to be optimistic and is easily impressed and persuaded. He also seems to have a close relationship with Mabel, due to the fact that she did not judge him by his true form. Even though he might be in a forced marriage, he still has feelings for Mabel in all seventeen of his hearts.
Mermando is a handsome merman with a scaled green tail that is darker towards his waist and lighter towards his tail-tip. He has dark skin, long, wavy, shiny brown hair and tiny mustache hairs under a long nose. He has a missing front tooth that was lost when he was hit in the face with a log. He has a deep and masculine voice with a Spanish accent, and speaks with a dramatic eloquence. He wears a red seashell necklace that contains a picture of his family.
As a merman, he can swim very well, but cannot survive for very long out of water. He can play at least one chord on the guitar and is multilingual, being able to speak English, Spanish, and dolphin.
- 115. "The Deep End"
- 204. "Sock Opera" (mentioned)
- 207. "Society of the Blind Eye" (pictured)
- 209. "The Love God" ( )
- 220. "Weirdmageddon 3: Take Back The Falls" (mentioned)
"I am charmed by your humor and bold lack of water wings."
"That wet sandwich does look delicious."
"There are some who call me... Mermando! This is because Mermando is my name."
"I was swimming with my friends, the mighty dolphins, in the Gulf of Mexico, where I was ensnared! ...The cargo was heading for Gravity Falls. Using all my strength, I tried to escape back home, but it was not to be... I would have died from dehydration, were it not for the kindness of the forest animals."
"Dear Mabel, I am home with my family, and I am very happy. Our first kiss will always hold a place in my heart. Technically hearts... As a merman, I have, like, 17 hearts. Horrifying but true! *More bottles on the way!"
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