I'm actually quite opposite to Dayeye in this topic, but we do agree on Vanica. So let's move to the two I don't agree on:
Dante - Narcissism
From very beggining when we meet him, he was looking down on others, thinking of them as inferior to him - even when his target, Yami, appeared in front of him his first reaction was "no one is looking down on me". Other than that, we also have his taste in women - both Vanessa and Grey became interesting in his eyes only when they showed their magic, a proof they are unique compared to other woman, proof they are worthy for him. And there is also his toying with enemies, fighting them to the very end just to satiate his own boredoom.
Now, I may don't have profesional knowledge on dark triad of personalities, but from what I found out, machavellianism characterized by not only lack of higher emotions (which Dante has, though only in extreme situations, like actually being hurt) but also with winning at any cost. Dante could have win fight with Yami and Aata if he didn't toyed with them.
Zenon - Machiavellianism
His lack of emotions is obvious. All the time he appear, his actions are cold calculated, aiming just to finish his task, no matter the cost. He could have captured William without even bothering about the rest of Golden Dawn, letting DD take care of them, yet he ordered elimination of them all, just to be sure no one would interfere. Then there is his quick reaction to Asta arm, and immiediate decision to kill him, because he may have cause trouble in future.
Of coure, I may be wrong, but I simply cannot see those two diferently.