i think the reason why he tested his strength on his own clan was to test out his mangekyou sharingan. from the looks of it, his sharingan deactivates as soon as mangekyou sharingan is performed so i guess itachi is in the process of mastering the technique.
anyway, i thought itachi was 12 when he massacred his own clan, but it says that he was anbu at 13. if he did do it at 12, then i guess he would've left the village right after therefor, not being able to receive anbu status. this is really weird because during the flash back, sasuke says that he is the same as age itachi when itachi graduated (7). which would mean that itachi was 12 since they are 5 years apart cuz sasuke is or should be 12 right now. but i guess itachi could've been 13 if one year has passed since the first episode til now.
also, i think there is a bigger reason to killing his clan than just 'testing his strength.' i kind of felt like he had another motive when he said 'it's important' (AA trans). i don't think it's completely different than to 'test his strength' but i think it branches off from that motive.
[img]i/expressions/face-icon-small-wink.gif[/img]Originally posted by: logic
Also, Mut@t@, i'm impressed with the way you can answer questions and what have you based on what the anime has presented so far. I know you've read the manga, but it seems that you never reveal anything that hasn't been shown yet.
Impressed and appreciatory.