I have to admit, when Lance interacted with them as a human, he handled their relationship quite well.
When faced with deadly dangers, he never took the initiative to reveal his formidable strength; instead, he let them solve it on their own.
The key point is, some of those deadly dangers might have been triggered by this old guy Lance himself.
As for concealing his true identity, he didn't seem to particularly care.
It's just that accepting Lance as not a human, but a Black Dragon, might take some time.
"Venus, what do you think about Lance's concealment of his identity?"
"I can accept it. Sorcerer-pharmacist Lance is Lance, Black Dragon Lance is also Lance, I don't care what species he is. I know that when he interacted with us as Sorcerer-pharmacist Lance, he never harmed or deceived us.
In my heart, even if Lance's true identity is a Demon, I would still accept him."
Venus truly didn't mind; from beginning to end, she never felt deceived by Lance.