To everyone saying Demi sucks, it only sucks in battle, but in early game it is a fairly good junction spell if you don't want to spend a lot of time trying to get a lot of high end spells for junctioning.
There are better options that are just as easily obtained though.
Off the top of my head, my general list of early-game junctions are: HP: Quake (armadodo cards) Str: Tornado (abyss worm cards) Vit: Regen (mesmerize cards) Mag: Death (tonberry cards) Spr: Curaga (tents)
With the added note that modding the Quistis card gets you 180 Triples which lets you give 2 people a VERY good junction (usually I put it on the 2 characters with Str-J early on, moving their Tornados to HP, and Quake to Mag)
You can leave off the Triples if you really don't want to mod rare cards so early, as well as skip slots that you don't have enough junction abilities to spread around.
Only real use for early-game Demis is to safely card if trying to avoid exp.
(I'm aware that meltdown and pain are also available, as are flare and holy, but in terms of bang for your time investment I think the above are best until better sources of spells are available).
http://www.geekologie.com/2008/08/25/ninja.jpg Everytime you see him, the phiefer's just so hype. He's dope on the board and he's magic on the mic. ~fidormula