The Mage Underground - "I have made this place a sanctum of healing and salvation! Why do you threat

Yeah, they get along great when both are harassing Merrill. 
Don't forget Anders, Mr. "People Should Be Free" being literally the only companion who approves of selling Fenris back into slavery. 

And Merrill so happy if Hawke let the sloth demon to possess Feynriel. Cute, isn't? 

And yet her words when dealing with Torpor are "I don't think we should be doing this." Plus if I recall she only approves when making the deal(which can just be to trick the demon) and not when it actually happens. But go ahead and change the narrative like you always do. 
Now actually adress my post. I want to see you excuse Anders' actions in the situations I mention. 

I saw a post on tumblr some time back talking about how Anders views Merrill and Fenris
it was quite thorough, but of course when I tried looking for it again I couldn't find it
it talked about how Anders views the both of them as obstacles, not just for being near Hawke (I have this head canon where Anders pines after Hawke even if they don't romance him)
but by what they represent;
Merrill is a blood mage, which is everything Anders hates, she was also able to deal with a demon/spirit without falling victim to it (at least with Hawke's help, there's no telling what would've happened during her Act3 quest if Hawke hadn't been there)
Fenris lived in Tevinter and had his whole life and world colored by everything he saw there, he saw how dangerous mages are, and is rightfully scared/wary of them

plus as I've said in another thread...they're people, people don't always get along
Hawke is just there being the red string that keeps them all together (which fits since the champion armor has a lot of red in it ^^)
and yes, Anders and Fenris get along swimmingly when they attack Merrill when she's at her lowest, but know what...Fenris also (in his own way) tells her to life up to Marethari's memory, Anders more or less just tells her she was stupid

Yes.
And if Merrill involved, Anders and Fenris are high five bros.

Anders harsh with Merrill – cruel and a jerk, undoubtedly. But he has every right to warn her – he knows well the danger, it was his personal experience. He wants to scare her because: "Most blood mages never get a second chance."

It depends – it's a possibility, that Hawke does nothing, or even tried to stop the rebellion. But even a possibility, that Hawke supports the rebellion, actively, and can continue the fight with Anders after Kirkwall. 

But even if Hawke "just" protect the mages from the Annulment, and help them to escape, s/he, as the (in)famous Champion of Kirkwall, helped to the mages, it's something. (Varric's epilogue, DA2) Hawke can be the face/name of the rebellion... or something (I don't know the best term)

Not to derail the current conversation too much but.....is Orsino really a "rebellion leader" like the opening posts insists?

I mean sure, he rebels against Meredith and her policies (sometimes with shady means) but that doesn't neccesarily mean he is against the Circle system as a whole. I bet several people wanted to change how Meredith ran things. But just because they wanted to drastically change that one chapter of templars/magi does not mean that they wanted to dismantle or rebel against the entire institution.

It could very well be that he just wanted the Kirkwall Circle to get more in line with how other Circles do things, or just something better while still being a Circle. I mean say whatever you want about Orsino (rebellious leader, harvester, shady character, etc.) but he was still mostly working within the system he was given rather going completely rogue like Anders did. And it's not like he didn't have that option either, seeing as how the mage underground had a substantial following in Kirkwall.

Ugh. You didn't read the intro post regarding this being no place for smug templar support, did you?


Besides...