Athrun Zala and Kira Yamato are best friends torn apart by war. Athrun and Lacus Clyne have been engaged since childhood. Kira and Cagalli Yula Athha meet and interact under unusual circumstances and are attracted or drawn to each other. Kira and Lacus develop a sweet, romantic connection. Athrun and Cagalli meet and form an instant bond of sympathy and attraction. All the while, Gundams! Explosions! Tears! How could anything good come of this?
Well, because SEED is full of sap and adorableness, good does come of it. Athrun and Kira confront each other and eventually join forces to stop the fighting. Athrun and Lacus confront each other, accept their true motivations and feelings, and part ways (and rejoin later) as friends. Kira and Cagalli turn out to be siblings, and...well, Cagalli accepts that readily enough and insists on taking on the big sister role even though they're twins, and one could assume Kira accepts it too, although it's a little more ambiguous on his side. Kira and Lacus triumph over war and hardship to be together, and so do Athrun and Cagalli.
And I ship it. The whole thing. It was my first real OT4. Sure, I'm not so big on Kira and Cagalli actually having sex, and I think Athrun/Lacus as a romantic pairing is pretty boring, but I think of them all as a family that happens to include some romance. Other OT4s with similar caveats have followed--Saber/Shirou/Rin/Archer, Lockon/Tieria/Setsuna/Feldt, Fakir/Ahiru/Mytho/Rue, Shizuru/Natsuki/Haruka/Yukino--but this was the first.
Also, since I pretend Destiny doesn't exist, the great OT4 never gets redesigned to exclude and fuck over Cagalli just because her voice actress pissed off the scriptwriter. Because changing a close-knit group of four people so that the only one of a different "race" is isolated and excluded solely for being a politically powerful woman with duties outside of her male love interest doesn't send creepy negative vibes at all, nooooo.
Day 02 - What was your very first ship?
Day 03 - A pairing that needs to happen now?
Day 04 - The pairing with the most chemistry?
Day 05 - The pairing with the least chemistry?
Day 06 - The best kiss?
Day 07 - The most heartbreaking scene?
Day 08 - The pairing with the most baggage?
Day 09 - The most believable relationship?
Day 10 - Why aren't these two married in real life?
Day 11 - What is your dream pairing?
Day 12 - Who had the best wedding?
Day 13 - What is your favorite television pairing?
Day 14 - What is your favorite book pairing?
Day 15 - What is your favorite real life pairing?
Day 16 - What is the absolute worst pairing?
Day 17 - A pairing you thought would never work out, but did?
Day 18 - What is the cutest pairing?
Day 19 - A pairing you've rooted for since the beginning?
Day 20 - The "can't stand the sexual tension anymore" pairing?
Day 21 - A pairing you like and no one else understands why?
Day 22 - A pairing you hate and no one else understands why?
Day 23 - A crazy love triangle/quadrilateral that worked out great?
Day 24 - A crazy love triangle/quadrilateral that worked out badly?
Day 25 - A pairing that was/would-be adorable, but could never work out?
Day 26 - A pairing that you hated and ended up loving?
Day 27 - A pairing that you loved and ended up hating?
Day 28 - A pairing that you will never understand?
Day 29 - What ship had the best proposal?
Day 30 - Your favorite ship forever and ever and ever?