in the drama, the traumatic loss of his mother turned light into a much more gentle person in the beginning
with her death, the role of “mom” had to be filled in the yagami home, and as sayu was much too young, and soichiro remained committed to his career over his family, the only one capable of stepping up to the plate was light
he took on the sort of responsibility expected of a girl. he cooked, he cleaned, he cared for his younger sister and for his emotionally distant father. this labor and its lack of reciprocity had a “feminizing” effect on him so to speak. he broke in the same way every girl does: he longed only for a simple life where he could be content and not stick out too much. he became an underachiever, a gentle young man, already worn down by a decade of responsibility.
but when he gets the death note, he gains a power that was unavailable to him as a child. it was initially his since of responsibility to his family and his caring nature that drove him to use it, but it was that promise of power that made him keep using it.
as the series progresses, light begins to change. he tells sayu to cook for herself, to wash her own clothes. he demands a seat with his father, and sayu pours him a beer just like she did for their father. he stops being kind to misa and begins to use her as a tool for his plans. he manipulates women in his path, consistently viewing them as tools and neglecting their humanity. the death note has given him access to manhood and the freedom that it provides that he was denied by taking on the role of his mother. the death note teaches him that masculinity holds power, and he gladly takes hold of it.
light believes this was his only option to unshackle himself; if he did not begin acting as a man (by way of violence against women, aka “toxic masculinity”), he would suffer the pain women experience forever.
but he was presented another option: L.
L rejects social norms, he lives as he desires, and it is only men L becomes close with. L seems to heal with light. light inspires something kinder in him, something that wants to care and be cared for. and moreover, L ignites a spark in light, inspiring him to achieve and challenge himself and be better.
L’s rejection of society and closeness with other men is the route light couldve chosen and did not. L begging him to confess that he is kira is also a plea for him to confess that he loves L. L wanted light to see the value in loving him, to see how much he could be with him, and that his embrace of the social values that had caused him this pain was not the only way to free himself from that pain
but we know how that played out.