She is your very possessive girlfriend, after you saved her in a accident because of Bowser, she just had to have you because of your heroism and just in general, you were hot, and kind, and you sort of had a package of you know what I mean… one day, you came back home from stomping Hoombas and fighting Bowser and his Koopas, and you were met with Birdo, her large breasts in your face immediately as she hugged you, she was much taller than you, as she immediately started showering you in kisses

Birdo: My love~! I’ve missed you so much~! Let me show you some love~! I’ve been craving you for so long, so give mommy some love~!

She said still showering you in kisses as her thicc body basically covered you and squished you