Alexander took Alec, Jace, and Isabelle to be his new students, since both Lightwood siblings showed great potential even without the extra angel blood.
Alec showed he is highly skilled and proficient in marksmanship and archery. While Isabelle show
she is highly skilled in armed and unarmed combat.,he weapon of choice was a whip, able to use it to exert power and control over her enemies.
For Jace he was taught by Valentine, so he was good with weapons and showed signs of being a great swordsman. At the same time, he showed the same arrogance as Valentine.
It is pure angel blood, due to an experiment performed on him as an unborn child, and this gave him special abilities superior to those of normal Shadowhunters'.
This pure angel blood didn't make him the same level as Alexander, but just gave him an extra blessing which was Rune activation, Jace can activate runes on his and others' bodies without having to use his stele. When he does this, his eyes turn gold.
Jonathan showed the same arrogance,but Alexander was able to get that out of him with quite a few fights.
So time passed and in January of 2005, the Hale Mansion was attacked by Gerard Argent and his fellow idiots. They ran after setting it on fire and Talia Hale was able to call Alexander for help, but even though he saved most of the family members present Talia died in the fire as she tried to go inside a save her daughter Cora.
Which was a devastating loss, while Derek Hale and Laura Hale were at school at the time of the fire and were thus the only two known survivors who sustained no injuries. Laura inherited Talia's Alpha power due to her being the second-in-command and heir to the Hale Pack leadership at the time of Talia's death. The two siblings were sent to New York by Alexander, where they would live for the next six years.
Among those missing or dead was Cora Hale and the injured was Peter Hale, who sustained 3rd-degree burns to over 75% of his body and went into a coma while his Werewolf healing recovered from the burns.
While Alexander was with Kaelie his girlfriend watching over Derek and Laura, who were slightly in shock and he could their sadness and anger raging inside them.
Alexander whispered, "The Hale family is in disarray."
Kaelie who was next to him nodded and replied"Yes, if they lost their mother and relatives,it will take time for them to heal from the mental wounds."
Alexander kissed Kaelie and said, "I will need your mind-healing expertise in this."
Kaelie smiled and giving nod replied"Don't worry I will take care of them."
Alexander was happy about this and knew both of them were in good hands,while he did decide to keep an eye on the Argents mainly Gerard and Kate,since there had been talks about them having a hand in the fire.