Bertie is a character from The Legend of Zelda: Skyward Sword. He is the husband of Luv, and the father of an infant child, and they live together in a house in eastern Skyloft. He works at the Potion Shop together with his wife; specifically, his side business allows Link to enhance the potency and effects of potions bought from Luv by mixing them with insects. His wife is rather demanding, and it is Bertie's job to look after the baby. He also appears a bit insecure of himself by the way he talks.
Similar Gondo, if Link is missing a single ingredient for infusing a potion he will provide Link with hint on where or how to obtain said ingredient. This makes him a useful source of information on where to find and obtain various Bugs. Most of Bertie's knowledge of insects that inhabit the surface comes from his secret infuser's handbook.
Bertie spends his nights tending to his and Luv's baby; shortly after Link completes the Lanayru Desert's Silent Realm, he remarks to Link that neither he nor the baby have slept for a long time, ever since the baby's Rattle was stolen by a bird. Bertie conjectures that the bird never left Skyloft with the trinket, and asks Link to look for it. Link eventually finds the rattle hidden in a bird's nest nearby, and brings it back to Bertie's house. Bertie is overjoyed, and Link is given five Gratitude Crystals for his trouble.
As many residents of Skyloft seem to be named after birds, it is possible that Bertie ("birdie"), when combined with his wife, Luv, are named after the lovebird.