No no, he wasn't aware. That's why he even said to his father that he will protect her if he does anything against her. Because he didn't know what his father was plotting. He was suspicious of something but he didn't know.
Anyway, Mr White's plan wasn't to make it difficult for Athy. All he wanted to do is putting Jaenette on the throne so that she could have a family (since he knows that her real father is a cunning shitty one)
We would never know what he thought about that but what I'm sure by re-reading it, that his goal wasn't to take what Athy had. And we could see that he didn't really like Jaenette's father. He feared him. He didn't want to go against Claude either since he didn't want a treason. But then, what did he want? Since Athy's uncle killed him, we will never know (unless Lucas does something like talking to souls) and that's a shame.
Anyway all I can say is that the Alpheus Father didn't seem that bad. But I'm sure Ezekiel will be an important part to put everything at its rightful place. I mean, he already understood that his father wasn't his "father" from just one meeting. It's only a metter of time before he goes to Athy and help her.
So please, don't say something that isn't true about that boy. He tried a lot in helping her. Now there are still things he doesn't manage. He is not a god huh. But at least, he understood quickly that something was off contrary to anyone (even to Athy) while Lucas knows a lot of things, but isn't suspicious enough since he thinks he can protect her. They both have their ways of dealing with things and are trying their best to be of help to Athy. Now it's obvious a god-like magician would be more of help than a mere human without mana. So given the situation, Ezekiel is really doing his best with what he is able to do. It would be fair not to find fault at Ezekiel while not finding any to Lucas when they both have fault (it's strange saying it's a fault but I hope you understood me)
So to conclude this, Ezekiel doesn't have a lot of power to protect Athy so he is wary of anyone that acts suspicious against Athy. He is vigilent and not just blind like Jeanette.
While Lucas has a lot of power and knows a lot of things but isn't vigilant enough (he doesn't have intuition or anyting like that) and in the end, is never there when Athy needs help (and ends up helping her after but not right at the moment)
Now I ship Athy with Lucas but I find it really unfair to judge Izekiel badly when he is trying really hard to protect the one he loves.
I actually love Lucas more than the Mr White's son (i forgot his name) because although Lucas was mean when they first met, he still help the princess when she's in trouble. But that Mr white' son, he knew his family plotted something evil but still didn't protect the person he love