The assault theory is as legitimate as the drugs.
Drugs has only been given serious thought since we learned he left during the night.
I don't think Fiona was leaving the child alone, she cared about him a lot. She may have had issues with alcohol and possibly some complex relationships with her extended family, but thought the world of her son. The only thing I could say on her parenting is possibly her over compensating, it was really important to her that her parenting looked excellent and understandably she wanted the child to have every opportunity to excel.
Those are normal things. Lots of parents in lots of different family situations do that.
The key indicates Noah wasn't letting himself in after school and that she was at home when he returned, I didn't have a house key at that age, if there was nobody at home the key was left under the flower pot.
I think she's a very attentive mother, knew her child very well but adolescence brings secrets to every parent child relationship. I think there may have been some fog about Noahs changing personality, again not that unusual, teens are hard. You drop the ball for a second and any number of issues can arise. It's happened in this house.
It's horrendous that this happened to the child, he should be here today, whatever was going on, stress, drugs, involved with people, an assault, fear, who knows? His life shouldn't have ended in this way. I don't know about Donal, he described him as the poster boy for missing children everywhere. I don't like it.