A couple of speculations and what-ifs around Tally Craven, Thinker Extraordinaire - Part 1
By the end of season 1, Tally Craven has a very complicated relationship with General Alder: Alder had her and her team mates execute a truck full of civilians, suffice it to say that Tally is NOT happy about this. And then the fight against the Camarilla happens and Tally sacrifices herself to save Alder's life, enmeshing herself with Alder's mind and soul, which, to say the least, is not the most objective viewpoint to land in.
In season 2, Tally is de-biddied but the connection prevails - and this is where my speculations start.
(I will split this up in two posts because otherwise this is too long to easily read.)
Scenario 1:
The reason why Tally is so distraught about killing the civilians is because she is deeply empathetic and could feel the civilians' terror and pain when they were killed. (This is not my idea but comes from the fanfiction “Lie Still on Nettles” by Anonymous (https://archiveofourown.org/works/33398428) and made me think: yes, makes perfect sense, so what if..)
When Tally was a biddy, she was privy to General Alder's surface intentions and emotions (as well as getting a fair dollop of caring for her and investment in her welfare); however Tally was not privy to General Alder's secrets or memories. I think this is actually canon because otherwise de-biddied Tally wouldn't be so surprised and shocked by the memory dreams.
So when Tally dreams of Alder's memory for the first time, it almost makes her go up the wall. It is one thing sharing the emotions of strangers who fear for their lives but quite another to feel the trauma of someone you know, someone you still feel close to. Tally wants it to stop and wants it to stop now. The dreams are so vivid, Alder's feelings still so familiar to Tally that she has trouble separating where she ends and Alder begins. Is it her hate, determination and terror or Alder's? If she dreams dreams like this every night, will there even be anything of Tally left?
Quite apart from the fact that Tally is considerate, she is the peacemaker, she respects other people's feelings and boundaries, wants them to feel safe and appreciated.
And now, Tally's choice depends on how much she trusts that General Alder will not harm her.
Scenario 1.1 - wherein Alder has aims and nothing will stand in the way
From her time as a biddy, Tally is aware that Alder has a relentless streak. It is possible that Alder was not always like this but she has certainly become it over the centuries of fighting, persevering and suffering. Alder thinks long-game because the short-game doesn't really apply to her anymore - her pain and age is distributed among the biddies, so she doesn't feel the full brunt of her own emotions; and Alder has been doing this for a long time and wonders if there are situations left where she doesn't feel like: "oh no, not this again". Alder is bound by the Salem Accords and insofar as she has any particular drive left it is the pursuit of her aim: with any means necessary ensure that what she thinks the welfare of witches can look like in the best scenario she can envision (given all the crap) is safe.
Alder and Tally are connected and Tally's pain will reverberate with Alder but if Alder is truly without scruple, then this will hardly matter.
So Tally goes to General Alder and reveals that she dreams of Alder's memories. Alder is intrigued for a moment - this has not happened before, how nice - and then, she is horrified. This is a leak of classified information, so classified in fact that this information only lives in Alder's brain (because for some reason, the military has not kept proper documentations on its own actions. (In real life, there is of course hush-ups but I think we would be surprised how much failings actually do get documented, the question is really more: who takes the trouble of reading through it and are there any actions taken in response)).
So this young cadet stands in front of General Alder, eyes all open and trusting, and Alder knows immediately that she has to squash this access as soon as humanly possible, with all means necessary. Tally Craven is a soft, naive idealist, and - quite apart from the fact that no one should see Alder's secrets - she is the last person Alder would want to have knowledge about her past and the conflicts in it.
Alder calls Izadora and discusses possible medication that will disrupt Tally's somnial wanderings. Tally is fully on board with trying to shield herself from Alder's memories, so she goes along with all the treatments. None of them work.
Alder thinks, how regretful, she loves Tally, she does; she just loves the fate of the witches in the world more. So Alder sends Tally and her unit out against Nicte Batan, well aware that Nicte has noticed the link between Tally and Alder, well aware that Nicte has a fixation on Alder and that Nicte will want to kill Tally in her obsession and jealousy.
Nicte kills Tally Craven, and Alder feels deep pain in her chest and in her stomach. She mourns Tally Craven openly - why wouldn't she: Tally is a former biddy, everyone knows that Alder has been very concerned about Tally's welfare - just as Alder is concerned about all witches' welfare, she might be the head of the military but she is a general of protection, mother and sister of the soldiers she commands.
And so the reign of Alder continues. All secrets keep.