Bottom is transformed into a person with an ass's head, but he is also transformed into the love object of Titania, Queen of the Fairies. This is ironic, the opposite of what we would expect, because Bottom is a lower-class weaver. We would expect someone of his stature to perhaps worship a queen from afar, but never, ever to be fawned over and beloved by a royal personage. Adding to the irony, while Titania is graceful and sophisticated, Bottom is a bit of a buffoon. For example, he is the ultimate ham in wanting to play all the parts in the play the mechanicals are putting on for the wedding feast.
Bottom is hardly an appropriate love object for Titania, yet, ironically, she has her fairies waiting on him hand and foot, while she weaves flowers into his hair. This is all because Oberon has had Puck infect her with a love potion as he wants her to give him the young Indian boy she has guardianship over. Shakespeare has fun with illustrating that love truly is blind, for the noble queen finds it impossible to see she has fallen in love with a fool.