I think the title Fen'Harel was simply meant to frighten people. They were presumably aware of wolves. So this is the ultimate big, bad wolf. Even Solas' own image of himself looks really scary. As he says, it sort of backfired on the Evanuris, because his followers started using it as a badge of pride. "We are followers of the big, bad wolf that the Evanuris are so afraid of" and Solas thought to himself, "You know that isn't such a bad idea", because then the slaves will get the impression that he really does have the power to challenge the Evanuris and that is why they are so afraid of him, when as he admits he really didn't.
The warning of the Evanuris actually acknowledges that his true threat was in his propaganda, his ability to persuade people to his cause. They speak of him as a humble wanderer, who seems so knowledgeable and speaks such fair words, but is really the Dread Wolf with his poisonous lies.
The story about the love struck elf simply reinforces the idea of doing what is necessary to achieve your aims. It is not about the morality of the story as relates to Fen'Harel's conduct, so much as how someone had a problem and Fen'Harel gave him a solution. It was up to the young man if he followed the advice. No one was forcing him to. It is quite possible that if the ruling class were as bad as Solas says, the elf might actually have gone along with it but that is not really the point of the story. I was joking really about Felassan reinforcing Fen'Harel's image. That didn't matter at all and trying to show Fen'Harel in some other light than a trickster might have made Briala question his links with the Dalish sooner. The story was shown to illustrate that the reasons why someone does something are important. Why did the young man consult Fen'Harel in the first place? Because he wanted to find out the identity of a girl. Why did Fen'Harel suggest he murder the other daughter of the king? Not because he bore her any ill will but because the young man had asked for a solution to his problem. He is making the point that Celene couldn't care less about the elves in Orlais. She isn't some enlightened monarch trying to make amends for the past. She has done all that she has done because Briala asked her to. Briala's efforts on their behalf are the reason that the elves are better off under Celene and if Briala was out of the picture, that would be an end of it.
However, when he says "You begin to think like Fen'Harel" and Briala says: "It was only logical...." as though she wants to defend herself from such an accusation, he does reply "That was a compliment, da'len". And Solas did get a lot of pleasure out of observing the Game. He also likes and is good at chess. It does suggest that Solas has a mind that thrives on solving problems, watching how other people do so and a very logical approach to things. This needs to happen, so I must do this. Again it comes back to the denial of good and evil or allowing emotions to get in the way of what must be done. Hence him cutting herself off from Lavellan because she is encouraging him to feel dangerous emotions when it comes to doing what is necessary. The white wolf fighting back against the dread one.