She and her brothers are the last surviving members of the Lannisters, assuming the pregnancy is faked. In this aristocratic culture the idea of a family dying out is horrifying. The Starks are down to three siblings, none of whom seem to have any interest in reproducing. The Targaryans are down to one survivor ( Danny) who thinks she is barren. The Tyrells, Freys, Baratheons, Tarleys, and Boltons are extinct, if you don't count Sam ( sworn to celibacy) and Gendry (illegitimate). Nobody knows about Jon Show's lineage.

Cersei needs to keep her family in existence -- it's a cultural thing, not personal affection.

@CharlesTheBold said: Nobody knows about Jon Show's lineage.

Are you sure about that? And it's Snow, not Show lol.

Of course Brann and Sam and know, and maybe a few others. I meant that nobody around Cersei would know. From her viewpoint she's surrounded by families that are extinct or dying out.

Historical note: Isaac Asimov, in a history article, pointed out that the War of the Roses (Martin's model) wiped out a lot of the English nobility, leaving the Tudors free to create a new aristocracy that owed its prestige to the crown and were unlikely to rebel. GAME OF THRONES is showing the wiping-out stage.

Killing Tyrion would simply gave her game up, which is to backstab Dani & her unsullied army.

Killing Jamie would lower loyalty in her army, as Jamie was renowned in battles and respected by soldiers, despite being Kingslayer. And would further sends suspicion to her newly found ally, Dani.

(Everything in the season is great, except Cersei's chemo haircut)

"(Everything in the season is great, except Cersei's chemo haircut)"

Cersei's haircut is designed to cover up the fact that her head was shaved by her enemies two years earlier. She can't regrow the hair, but she can make it look distinctive.

maybe she has FPHL, or the actress is from Australian?

https://www.niams.nih.gov/health_info/alopecia_areata/

Anybody would be stupid to trust Cersei at this point. Hopefully Tyrion has used that wit of his.

@Strawberry Shortcake said:

Cersei could have had both her brothers killed, yet something stopped her, and she let them go unharmed. Clearly it is not the taboo of kinslaying - she had no qualms about killing her uncle and cousin. So what stopped her?

If she had, Daenerys would have had King's Landing burned to the ground on the spot. It wouldn't serve Cersei anything other than quick revenge , followed by even quicker reprisal from an enemy with three dragons worth of firepower.

Her qualms we're never an issue, the issue is strategy and self-preservation.

Her best course of action is to feign alliance and then double cross them later which is exactly what she chose to do.

@MangeSkeevesOutKlam said:

@CalabrianQueen said:

It wouldn't serve Cersei anything other than quick revenge , followed by even quicker reprisal from an enemy with three dragons worth of firepower.

2 dragons *

Too soon lol.