I understand this is a tad low-brow for you beard-stroking, cloud-headed meta-philosophers down in these forums (that was meant as a compliment, I promise), but I still thought it was an interesting area of the lore, and an interesting plot point for Bethesda to read and to use (apparently, they use these forums too), so please go easy.

Anyway, we know from the in game book "The Great War" that Titus Mede is rumoured to have used the sword Goldbrand in the Battle of the Red Ring Road. Since this is an artifact of Boethiah, and one would imagine she would only bestow it on a champion of hers, it leads to the conclusion that Mede contacted and beseeched Boethiah, and perhaps other Daedric Princes, for aid in helping him save his Empire.

Boethiah may have several motivations for helping him:

1) She dispises the Altmer since they are the antithesis to her people, the Dunmer, and would seek to eradicate their culture and bring them back to Anu-esque religions.

2) The Thalmor claim to be the Rightful Rulers of the Empire, and Boethiah's sphere specifically pertains to the unlawful overthrow or withholding of power.

3) She is Prince of Deceit, and Titus Mede decieves the Thalmor by riding out of the Imperial City and makes offers of peace. That does not seem like the noble, forthcoming Imperial qualities that someone who tries to claim Akatosh's divine Favour would display, no matter the circumstances. Whilst he may be a weak man and desperate, it may be possible to contrive a Daedric Hand here.

So, do you people of the lore forums think this is a reasonable guess? Could Titus Mede II have sworn himself to Boethiah in return for her sword, Goldbrand, and hence her "Divine" aid in battle? If so, then perhaps his death at the hands of an agent of Sithis was simply the fulfilling of the pact. Perhaps Mede's soul now resides in Boethiah's realm, him having made the ultimate sacrifice for his Nibenese and Colovian charges.

Thoughts?

It's quite possible. Others have theorized that the Altmer now represent the legitimate authority on Tamriel, possibly because the Imperials mandate from Akatosh is now different. Of course, Mede wouldn't be the first emperor to make a deal with the Daedra: there have been hints that Tiber Septim had something to do with Molag Bal, and Sanguine was a resident of the Imperial Palace under at least one emperor (Reman I or Antiochus, can't remember right now).

It's worth mentioning that his brother, Prince Attrebus Mede, became bound to Malacath as a result of the events of Lord of Souls.

When Attrebus and Sul find themselves within Namira's realm, they are viciously attacked by a creature within the darkness. Attrebus is practically killed in the process, as the attack leaves him completely disemboweled. Sul manages to save the both of them with what little strength he has left by opening a portal to another realm. Attrebus then begins dreaming of himself as a teddy bear who's lost his stuffing, with something putting his stuffing back in along with some ash. When he finally wakes up, Malacath eventually reveals himself to Attrebus and Sul and converses with them about their mission. After their exchange, Malacath looks to Attrebus and says, "And you - if I ever have need of you, you will know it."

This seems to suggest that Attrebus had become bound to Malacath as a result of the Daedra Lord healing his broken body, especially considering the images Attrebus had in his dream. Perhaps Attrebus's involvement with Malacath drove his brother to make bargain with the very Prince that acts as Malacath's antithesis. We're never told what happens to him, or whether or not he's still alive. It'd be interesting to find out that Attrebus is Titus II's successor in the next game.

What makes you assume Titus II is Attrebus's brother? One Hundred and Sixty Years have passed! Titus II could easily be Attrebus's Great-Grandson