"I remember six of them, their faces are engraved in my mind. As for those acting behind the shadows, I'll be able to find them too, when I finish them all then it'll be her turn. I want her to feel cornered, helpless and betrayed, a revenge is never sweet if it isn't done the right way."
Although he was talking about those who tortured him and caused him to love a life worse than even a lab rat, Arthur's voice was relaxed and his expression was calm.
It's like he was stating a fact and not speaking of what'll happen in the future. Lucy nodded her head in confirmation, no matter how he wants to pay back his debts, she'll forever support him. She even found some of the culprits and have a firm lock on Claudia, who is clueless about their relationship.
In fact, Claudia would never expect Arthur to be alive, from her perspective, he died on that fateful day and he had been 'properly' buried while she took control of his companies and wealth.