Hey buddy, nice idea!
Things which are making this piece static:
1) Compostion- youve slapped both right in the middle of the canvas which means that they eye has a very boring straight line from the eyes/mouth of the beastie to the dude in the middle. This can be done but it takes very fine handling, have a look at iconic and cross composition here:
http://www.cgsociety.org/index.php/CGSFe...n_tutorial one of the most comprehensive tutorials ive ever read on composition.
Oh and in 99% of circumstances NEVER use a square canvas. it makes things extremely difficult unless you are doing some crazy iconic/symbolic stuff. I work at 7000x3000px personally which is approaching cinematic, or 5000x2000px if my machine is slow.
2) Values- a killer. You have the darkest bit being the mouth of the beast, which makes no sense in terms of atmospheric perspective with the knight being lighter. Also that weird bit of black by the tentacle on our left. Set it up- near black foreground, dark grey near midground, light grey far midground, lighter grey (or darker if you want a somber mood) for background. The tentacles should be reaching out into the foreground I think because at the moment nothing is placing the camera.
3) Lighting- Youve got this really bright blue lighting from that back which is pulling a lot of focus. Not really sure what it is, and its just becoming another element which is confusing things. i would just have soft ambient back lighting if its in a cave, but it depends what the light source is. If its natural light, it is too blue at the moment I would say, and too blurred. You could have shafts of light penetrating through the cave and landing on the beast to pull focus?
After all this you also have some strange pale yellowy green front light from an anonymous source- define define define your light sources. Maybe its a torch which the knight is carrying?
4) Colour and focus- you need to set your main point of interest, then your secondary, and maybe a tertiary. This is a called a focal hierarchy, and is very important. Focus gets pulled to areas where there is a large degree of saturation, contrast, or where form is made up of smaller shapes (ie more detailed). At the moment it goes ( for me) #1 Blue light #2 Monster face #knight/tentacles, but none of these are really holding my eye. Go into some hard edged detail in some of these areas to keep the eye interested and they piece will gain a lot. Think about hard vs soft edge, small shape vs big shape and desaturated low contrast- saturated contrast.
Sorry if this was a bit of a ramble but I think this could be an awesome piece if you really push these factors a bit further, I attached a quick paintover I did (sorry its really quick, im meant to be working right now... whoops.), couldnt decide what the secondary light source was so will leave to you. Do thumbnails first and work from there every time to establish your composition ( i dont do this enough and I ALWAYS pay for it).
All the best man, I hope this wasnt too harsh I dont mean it to be, i just want to help push you to levelling up like everyone on CD does for me :D