Just putting in the room:
I am very sure that Cortez is Chavez.
Not because of what we see after the credits of Dreamfall. Not because of the similiarities in description.
Why was Brian in Arcadia? What is he doing there?
Well, the first impression is "He was curious and went there on his own" or "Cortez told him about it and since they were friends, he offered a description to it"
But it is dangerous for non-shifters, a Kin would know that. The daughter of the white Kin shows in Dreamfall that she knows about the realm of Storytime. So it can be assumed that Cortez also knew about it as a kin, especially since Storytime is NEITHER Stark nor Arcadia, so even if he is clueless about Arcadia, he would know just as much about Storytime as the white kin. So why was Cortez willing to risk the life of a human, a non-shifter, by sending him from Stark over to Arcadia? Especially since we see in the actual TLJ story, that he is compassionate and emphazises a lot with how everything tends to go wrong here and there.
Guys, just think strongly:
What PURPOSE did Brian serve in Arcadia?
Well, Cortez suggests that Brian is responsible for what?
For sending April back home.
How does she do that?
With the clock of Cortez.
What does the clock do (other then sending her indeed back home)?
It stops the very second that Cortez dies.
Cortez didn't send a human in its demise because it was curious. He wasn't sadistic and thus played a game of "Let's see, if he survives". He as the kin knew about what would happen, the trouble that might rise (because prophecies and stuff, like we learned plenty of times in TLJ), that a shifter might have to get to Arcadia to prevent total chaos AND would need help to get back again. So he sends Brian with the extremely important task to Arcadia to - 200, 300 years later - help April get home, so she can continue with her quest.
I would even go further and say:
He gave the clock to Brian and then left it in Aprils possession for one simple reason: to protect himself.
The clock seems to be strongly connected to Cortez, more specifically his life. It reacts strongly and definite about him being dead or alive. And McAllen might have known of the clock (sooner or later), since he obviously dislikes his brother more then everything else. When he captures Cortez, he steals his dragon gem and imprisons him, but he didn't kill him despite the fact that Cortez might, would and finally did show to be an obstacle in McAllens plans (because, if Cortez wouldn't have saved April, then she wouldn't have been able to save Adrian, to convert Gordon to good, etc). Maybe, because the clock has to be close to Cortez to react? Would Cortez have been immortal, if the clock would have stayed in Arcadia? THAT I obviously don't know xD
But I think, that IF Cortez would have had the clock in his possession while being in McAllens custody...he might have died much sooner, leading to him not being able to save April on the roof.
Taken, that the clock is not only of matter to help April shift, but to actually give notice about his life.
I personally think, it is a very important thing about the clock stopping the moment that Cortez dies. It isn't "just" a journal entry, April says it OUT LOUD. Every player will come to hear her say "Cortez clock stopped. Oh, God...his heart! That's what Brian said Cortez called it, his heart", giving the very strong impression that the clock might have mattered a lot more then we thought it did.
And - just as a random thought:
What has April done with it afterwards?
In Dreamfall is mentioned that she couldn't shift back to Stark, that she was trapped in Arcadia. So it is likely to assume that the clock also didn't help with the shifting anymore at this point. It had become a normal clock, only with the difference that it wasn't working. April doesn't have it in her inventory or visibly on her body in Dreamfall, so did she loose it? Or sell it (a BROKEN clock)? Maybe melt the clock and make something else from it?