She is referred to by Mr. Briney as "darling", journeying the sea alongside him.
In the anime
Peeko and Mr. Briney
Mr. Briney was revealed to have met Peeko one day while he was fishing, when she flew down and landed on the top of his head.
Peeko first appeared in On a Wingull and a Prayer! when May asked him for a way to get to Dewford Town as Ash and his friends were lost. May noticed Peeko and was willing to interact with her, only for Peeko to shy away from her due to the fact that she only trusts Mr. Briney. This changed when May brought out Pokémon food. Later, she was kidnapped by a Team Aqua Grunt who was in disguise as a Devon Corporation worker earlier to force Mr. Briney to give him a boat to meet his partners. When the Grunt was about to get away on Mr. Briney's boat with Peeko, Team Rocket interfered using their mecha to steal both Peeko and Ash's Pikachu. This was interrupted by Brock's Lotad's Water Gun which stopped the mecha. With Peeko still trapped in the cage, the Team Aqua Grunt took her and drove away on Mr. Briney's boat. However, Mr. Briney had a Wingull-shaped boat ready which was modeled after his Peeko. He took Ash and the others, and they chased down the Team Aqua Grunt. The two boats raced around until Mr. Briney had his boat jump up to block the boat the Grunt was riding on. With the Grunt stopped, Peeko ended up being returned to Mr. Briney. This did not stop the Grunt as he ended up escaping on Team Aqua's submarine. With the Grunt gone, Peeko and Mr. Briney were reunited.
Peeko appeared in Sharpedo Attack! where she was sitting on Mr. Briney's shoulder during the boat ride to Dewford Town. Along the way, they encountered some Sharpedo when May and Max were swimming. Mr. Briney had Peeko fly to where the two were and they got picked up by her. However, Taillow had to help out since Peeko's strength wasn't enough. Later, when the group docked on an island, Peeko participated in luring the leader of the Sharpedo by serving as some sort of transportation while Ash got the leader's attention. The leader came in and closed the area off, trapping the Sharpedo leader. After clearing the Sharpedo problem and taking the group to Dewford Town, Peeko was last seen waving goodbye to them while she and Mr. Briney set sail back to their hometown.
Personality and characteristics
Peeko was only close to Mr. Briney as seen when May tried interacting with her only for Peeko to hide behind Mr. Briney. Also, Mr. Briney is the same about Peeko. He even modeled a ship after her. He really cares for her as seen when she was kidnapped by a Team Aqua Grunt, he sailed on his boat that was the shape of a Wingull and chased the Grunt.
Like in other game-based adaptations, Peeko appears as a dainty Wingull that belongs to the old fisherman Briney. Briney endears her greatly, calling her "Peeko-poo." She first appears in Blowing Past Nosepass I where she found Ruby caught in the old man's fish nets. In Stick This in Your Craw, Crawdaunt I, Ruby was officially introduced to the two and his rescue was explained to him.
In the next chapter, after a Crawdaunt attacked their ship, Peeko distracted the Crawdaunt by attacking it when Ruby was trying to save Mr. Briney. However, Peeko ended up getting a broken beak as she charged straight into Crawdaunt's armored exoskeleton. This was when Crawdaunt's Shell Armor Ability activated, which prevented it from getting hurt by Peeko's attacks. Ruby ended up nursing her beak and healed her wound (he also adorned her with his "brand" of fashionable make-up). When Mr. Briney dropped off Ruby at his destination and met up with Sapphire, Peeko sailed away along with Mr. Briney.
When at a restaurant, Red wonders if Mr. Briney was going to eat his meal, which appeared in the shape of a bird. Mr. Briney reveals to the group that it was actually his compainion, Peeko, and that he simply enjoyed dressing her up. Afterwards, Peeko becomes affectionate towards Clefairy, often hugging him, much to his displeasure.
Mr. Briney refused to give Peeko to Team Magma and Maxie after they demanded her from him. They play "tug-of-war" with Clefairy, using Peeko as the rope. Mr. Briney stops the game and rescues Peeko, giving her the option to fly away. Team Magma and Clefairy chase after her, with Clefairy using a hot-air balloon as means of flight transportation. The balloon lands on Peeko, who flies away from it, revealing that she neither wanted to be with Team Magma nor Clefairy.