I've been playing him since day one so I've heard the voice lines a million times and I've come to my own conclusions in regards to them.
(Unless Riot confirmed it) First of all, I don't think Nora is dead. Rather, I think she's possibly either his current girlfriend or wife. Cypher says that he has to protect his family because he can't bare the pain of losing them again. That implies that he had a family before, either his blood relatives or a wife and possibly children, who died. I came to the conclusion that Nora may be a romantic interest of Cypher's because of the April Fools event earlier in the year. One of the "dates" seen was 2 bikes, with Cypher's hat on the handlebars of one of them, and a bouquet of flowers next to them. Cypher also stated in the "Agents of Romance" screenshots that he's married. Of course, that's not confirmed canon at the moment, but I'm inclined to believe that Nora is the mystery woman Cypher is married to, and who he went on a date with during the in-game event.
2nd, Cypher seems to imply that some of the agents have children in one of his voice lines: "Let’s see what I have to use. Pictures of their children? Wow, way too dark." His unwillingness to use pictures of their children as threats, as well as this line: "You’re lucky I’m generous... or else you families would be next" also lead me to believe that his family was killed. He doesn't appear to want to hurt the families of his enemies, nor does he appear to want to use their families against them. Its entirely possible that he wants to spare them the pain of losing their families since he already knows what its like.
3rd, his line when he gets revived by Sage is "For a moment, I saw them." which is kinda just depressing. Its of course being implied that he saw his dead family when he died.
4th, Cypher is a kleptomaniac who also spies on everyone. For example, Breach says: "Cypher, stop bugging my equipment with microphones. You're worse than INTERPOL." He's also implied to be a hacker, since he states he wants to try and hack the enemy Brimstone's bracer, and he also has everyone's passwords. He also "borrows" from everyone else, mainly Breach and Killjoy from the sound of it. He's also implied to harvest the corpses of his enemies for spare parts.
5th, Cypher knows his way around the dark web, as is implied by a line between him and Killjoy: "Hey Cypher, think you could show me around the dark web one of these days?" "Oh... Oh dear, no, sweetheart! I must protect you."
6th, Cypher may or may not have killed in the past based on this line: "Ah, you forget. I've always been a killer." Though, its also implied that he doesn't really enjoy it: "You're dead and I didn't feel anything, not even a thrill."
That's all I have off the top of my head. I feel like, perhaps, some of this should be added to his Wiki page, if its allowed to be. I'm afraid I'll mess something up if I try to edit it myself, so I'll leave it to the people that know what they're doing. I also apologize if all this has been brought up/speculated about in the past. I don't interact with the greater Valorant community.