Are we quite sure that Malacath is Trinimac? Sure, I know that Boethiah "ate" Trinimac way back when and then defacated out the deity which we call Malacath; however, is there really that much evidence that that's what happened?

First we'll look at http://www.imperial-library.info/content/changed-ones

In my opinion, this is the primary text on the change of Trinimac and his people into Malacath and the Orcs. First, notice the name: The Changed Ones. Chimer translates into Changed Folk. It seems to me that the text is referring to the Chimer. Also, throughout the text when using the pronouns "he","his", and "him" the writer refers to Boethiah. The text ends with this line,"It was easy then for his new people to become the Changed Ones." This implies very obviously that the followers of Trinimac became the followers of Boethiah; Chimer, not Malacath's orcs.

Now we'll take a look at http://www.imperial-library.info/content/true-nature-orcs

This text seems to have been written from farther in the future than "The Changed Ones". It is more a summary of previously known knowledge and new enterpretations rather than an original report. I only wonder where the author got the idea that the followers of Trinimac became Orcs. The only other document of the event states that they became Chimer. Another discrepancy with the document is the impression it gives that the Orcs had very little land from the get-go. The PGE1 tells us that before the Redguards came the Orcs thrived in the Hammerfell area, and only when the Ra Gada chased them out were they restricted in area claims.

Also, it is said that Malacath resides in Oblivion, though not exactly being a daedra. As we know, the Aedra are planes of infinite mass which orbit nirn. If Trinimac simply turned into a Daedra in the expanse of void, where did all that infinite mass go? Now, if Trinimac remained an Aedra, simply one too embarrassed or proud to admit his true identity as the "Dung of Boethiah", one which was tainted by the Death-Life cycle in the killing of Lorkhan, might he just be the Death-Life god? That's right, forget Trinimalarkey, how about just Trinimarkey? If Trinimac is simply Arkay then that explains how infinite mass could both be destroyed instantly and created instantly (In Arkay's Apotheosis), it simply wasn't. Trinimac became Arkay, the plane continued to exist albeit a bit differently.

If you don't like the physical example, how about a metaphysical one. How does an anuic deity, one of the most anuic actually, switch to being padomaic? It certainly doesn't occur in the middle of a Kalpa. Of course there's Mehrunes Dagon who was once either an Aedroth or one of the Magne-Ge; however, he was changed during the untime of the dawn between kalpas. I would assume the same of Meridia, and she was one of the Magne-Ge anyway.

The next piece we'll look at is http://www.imperial-library.info/content/father-niben, a biography of Topal the Pilot, the greatest Aldmer explorer to ever live.

Topal was the only explorer set out to find Aldmeris to return alive, as well as the Aldmer who discovered the mainland of Tamriel. He first landed on Tamriel in the Iliac bay and the first intelligent race he encountered were, you guessed it! Orcs. If Orcs were present in Tamriel before the elves, then I think it's safe to reason that they weren't the followers of Trinimac altered after he was changed to Malacath. It makes far more sense that they were the people of another deity, one who was a patron to all goblins and their like, one such as Malacath. But how did Malacath exist during the same time as Trinimac?

Conclusion: They aren't the same person, Malacath is the daedroth Malooc, Maloch, Malak, Malauch; Patron of Goblin-kind. Malacath has existed since the creation of Oblivion and continues to do so in current days. After Boethiah "consumed" Trinimac, the aedroth was altered into the deity of Life and Death, Arkay. Either too ashamed, embarrassed, or simply unaware of his past Arkay left the claim of Knighthood under Auri-El. Malacath, the daedroth, falsely took the claim to further his own goals and his people recognized him as such.

This is why there is no inexplicable loss of a planet recorded, why there is no mention of a new one either, why Topal the Pilot saw orcs in the Iliac bay far before the Aldmer had colonized the mainland, and of course, how an aedra turned into a daedra mid-kalpa and completely switched his chaos-order alignement: he didn't.

Well, I hope you people enjoyed my little theory here. I do hope you find some holes to poke in it. Have at it!

I'm just jumping in here to say something I've said before http://www.gamesas.com/topic/1471872-miscellaneous-lore-questions/?p=22968980: Father of the Niben is an incredibly unreliable source, and should probably not be taken at face value.

The thing is... Arkay is Orkey who is Malacath who is Trinimac.

This is from the Five Songs of Wulfharth. Noticed the part on 'Orkey's folk'. Even it's a small statement, it's actually quite important because it established Orkey's connection with Malacath and Trinimac as well as Arkay, God of Life and Death.

I'll show you the whole quote.

From Varieties of Faith:

Orkey's magic connects to the lifespan of the Nords. He can shorten them. Pretty much points to Arkay, God of Life and Death.

And then there was Malauch. Again from varieties of faith.

Notice the previous quote, 'bound them to the count of winters'. Another connection to Malacath. We can't really ply Malacath from the equation considering his intertwined as well.

There's more but damn, Malak can do a much better argument. I'm not really the expertist in the ManBearPig theory. As for the Father of the Niben. The problem is, the show down between Trinimac and Boethiah happens in the Merethic Era. During when Time is still not linear enough to be measured properly. Something from the future can be in the past, or the past is the future, or the present is the past... or, or, or, err. That's why there are account of Orcs before the Aldmer.

It's not the narrative at fault, it's Time making the ye olde contradiction again.

Malacath is the ghost of Trinimac.