What do each type of flower tattoos mean in regards to the emotions of the one who severed the bond? And what types do M and J have?
They are reflection of the one who sever the bond and why they would commit such an act. Generally the flowers are following the conventional flowers languages but it could ones that are more specific to someone's culture. It mainly ranges from pure hatred to sadness as not everybody is truly happy when the bond is severed. A mutual severed will have the flowers grow from the palm to about last the worst while the other type will have it grow to about midway the forearm.
M hate their marks for a reason. It's a daily reminder that their soulmate truly despised them despite being together for so long. They never even knew until they saw the marks showed up on their arms. They wonder what they had done to have caused so much anger and resentment in their soulmate. Candytufts (indifference), buttercups (childishness), orange lilies (hatred), tansy (hostile thoughts), petunias (resentment), and the crown one, the black rose (you're dead to me).
J is more sorrowful. Their soulmate could no longer be with them and they decided to sever their bond so that J could be happy. They were against the idea but relented after hearing their soulmate reasoning behind this decision. They still don't know how to feel despite how long ago it happened. Bleeding Heart (heartbreak), forget me not (remember me), purple hyacinth (sorrow and regret), desert rose (resilience and enduring) bellmore (hope and pain), and lily of the valley (return of happiness). These flowers are wilted for unknown reason that people around them don't understand but J secretly knows what it is in their heart.