In my trilogy, the protagonist and deuteragonist share a mental link, allowing them to communicate with each other telepathically. A side effect of this telepathy is that they enable the duo to observe a series of dialogueless flashbacks that delve into their respective pasts. These flashbacks allow the audience to form an emotional connection with these characters and understand them better, as these sequences recount essential events in their lives that irreversibly shaped them into the people they are.
There are three key reasons why these flashbacks lack dialogue:
I can't write good dialogue to save my sorry hide, and most of the dialogue I've come up would leave Ehren Kruger and George Lucas awestruck
It makes my job of disguising the deuteragonist's identity from the protagonist and audience significantly more manageable, without making characters use her real name continually and killing all sense of mystery right out of the gate (it's hinted that she is Jeanne d'Arc and the protagonist discovering her identity via her flashbacks is a significant plot twist)
I don't have to come up with some very contrived reason as to why characters staring in the deuteragonist's flashbacks can speak perfect modern English
In his flashbacks, it's revealed during the protagonist spent his youth in fending for himself in poverty and only managed to survive by falling with a gang of homeless youth. Though he was initially standoffish, he eventually grew immensely fond of their company and fell in love with a girl who gave his life meaning. However, that ended when a close friend betrayed him and nearly killed him, leading him to believe that humans are predatory animals that only care for themselves. Although he doesn't use what happened to him as an excuse to justify his nihilistic and selfish behaviour.
The deuteragonist's flashbacks borrow heavily from Ali Alizadeh's The Last Days of Jeanne d'Arc, which unapologetically explores the harsh and brutal reality of the Hundred Year War via Jeanne's perspective in media res. Throughout the novel, Jeanne faces the hideous slaughter her idealistic mission unleashes by getting a front-row seat to the many atrocities committed by the Anglo-Burgundians and her fellow Armagnacs. Rather than being flat-out misery porn, these flashbacks depict the deuteragonist coming to terms with the consequences for her actions and strengthening her resolve to end the Hundred Year War by using her faith as a shield.
This leaves me with two problems:
My reliance on showing rather than telling means that I'll be unable to get specific plot elements across to the reader
I can't use dialogue for characterisation, making difficult for me give personality to side characters featured in these flashbacks
How can I write around these issues?