Xellos is full of nothing if not the selfless spirit of giving.
Five Gifts Xellos Gave Filia For Her Birthday
The First Gift: the Gift of Laughter
The day before Filia's birthday, he anonymously gifts her with a full set of exploding tea cups of his own design. (On sale for a limited time! Order now and receive a FREE bonus farting tea cozy! Makes for great party favors!) Each cup features a small reproduction of his portrait artfully painted on the porcelain. He is sure she will appreciate the light-hearted reminder of the time they shared traveling together.
The Second Gift: the Gift of Even More Laughter
He sends the farting tea cozy separately.
The Third Gift: the gift of sensuality
...Along with the finest in antique erotic publications - The Secret Life of Dragons, by Madam M_____. (From the back blurb: "The ancient and majestic race of golden dragons are well known for their reserved public demeanor - but less well known for their lusty adventurousness behind closed doors. Come join us on an illuminating and educational exploration of this most secret life of dragons!") Only the best for his dear friend Filia, of course.
The Fourth Gift: the Gift of Beauty
The night before her birthday, he redecorates the entire exterior of her antique shop with hundreds of giant pink ribbons while she sleeps. He's sure she will approve of his taste. That is, if she can ever manage to open the front door again.
The Fifth Gift: the Gift of Friendship
Well before the big day, he had taken it upon himself to send letters to Lina, Gourry, Amelia, and Zelgadis, inviting each of them to attend "FILIA'S SUPER-MEGA-GRAND-EXPLOSIVE BIRTHDAY BASH!!! FREE FOOD." It was a little difficult to track them all down in time, but for Xellos, any effort is worth bringing old friends together to celebrate a happy occasion.
He waits in hiding to observe her screams of rage - ah, that is, her exclamations of surprise - on discovering his thoughtful gifts, until their old companions show up at her door. And then, upon beholding her expression of abject horror - no wait, that would be pure delight - he can no longer contain his urge to sweep in and confess to all of his selfless acts of generosity.
The subsequent explosions and mass destruction are all the thanks he needs.