I think it would be hard for any mother to kill her son, even a sociopath like Joffrey

She's so not "any mother" by this time, or just any woman, that I do see it as a Cersei-specific limitation. I would (as a show-watcher, not book reader) see her as wanting to get ahead on her son's achievements, but also appalled by him-there's no woobification there, or maternal principle past selfish DNA. I'm trying to put other mothers into a similar position, but I can't even get nearby.

I don't think there's only self interest between Joffrey and Cersei. That's a part of it, yes, but not all of it. I think she sees clearly that he is a monster, but I think she also sees him as her son and she loves her kids. I feel like both in the books and in the TV show that's one of her bedrock characteristics. Maybe she loves Joffrey primarily because he is a part of both her and Jamie (and Jamie is the most important person in the world to her not named Cersei) more than for his own merits (such as they are) but I think she does love him. I do agree that there's no woobification there on her part, though. She clearly knows what he is. She's probably done more bad shit than Joffrey at this point anyway. She's definitely got a higher body count. I figure she looks at him and thinks, "Eh, he's my monster after all."

I figure she looks at him and thinks, "Eh, he's my monster after all."

Plus, you know, it's good to be the Queen Regent.

Better than being thrown into chains by your son. Poor Cat. Not that Robb isn't between a rock and a hard place, but still . . . Your husband gets murdered and your daughters held hostage (well, one of them is on the run pretending to be a boy but she doesn't know that); your two younger sons appear to have been murdered; your older son has you clapped in irons for freeing his political foe in order to (maybe) ransom your daughters; you wind up with an unsuitable daughter-in-law who costs your son desperately needed war time allies; your dad dies, ugh. I know it's not so good to not be the Queen Regent, that's for sure.

I don't think there's any question that Cersei loves Joffrey, and Tommen and Myrcella. Knowing Joffrey is a terrible human being isn't going to change the fact that she's his mother.

Where in the show do you see love for Joffrey? I don't see the same kind of concern that I see from Catelyn, which also aligns with typical maternal love and concern that I'm used to in the real world. I can see why one would assume she loves him, but since so little here is normal, especially with her, if she doesn't show it in some way I can parse, I'm not going to say it's there.

There's no question for me that Cersei loves his kids, even --especially -- Joffrey. He's her golden boy/Frankenstein monster. He's just harder to control than she anticipated.

She also tells Sansa "Love no one but your children; in that a mother has no choice." She sees her love for her children as a weakness she's stuck with.

especially -- Joffrey. He's her golden boy/Frankenstein monster

Yep, this.

Where in the show do you see love for Joffrey? I don't see the same kind of concern that I see from Catelyn

I think almost everything Cersei does is out of love for Joffrey. She's not at all affectionate like Catelyn, but I don't see a lack of love for her hideous monster son.

I will respectfully disagree outside of the selfish DNA mentioned above. I don't know what any kind of love would look like on her face, but I don't see her having love for Joffrey as a person, or as the specific son he is. Glory of her heritage and the Lannisters in general, sure. He is indeed her golden boy. But I just don't feel anything personal there, mostly that he is an important piece in her plans and heritage.