It would a lot easier to show you but a posting makes it harder to describe but you are trying to get two opposing light objects in the same picture with a limited function camera when compared to the capabilities of a digital SLR.
Your shooting situation you described requires some indirect lighting to be placed upon your son while leaving the lite pumpkin either by his side or in the background...untouched by the indirect light source. One challenge will be to capture the pumpkin glow before your childs face lite by an indirect light source highlights in the photo to a point it 'burns' - looses detail.
You will need to experiment and try different lighting arrangements, since you are trying to bring to oppposing light requirements together in one photo with a mid-range camera. I shooting istuation could be like a dark room lite by a cracked door allowing a controlled light source into the room where your son would be placed...the pumpkin in the unlite part of the room, but close to your son. Depth of field could also become an issue due to the lighting situation, your lense capablities, and the distance between your two subjects.
Personally, I almost always avoid flash photography for a variety of reasons. You are simply needing to shoot what is called an exisiting light photography and these types of situations can become a challenge if you are unable to control the lense f/stop, ISO and shutter speed. No flash is used but you will need to stage an indirect light to highlight your son's face while no making your son's face 'burn out' in an effort to capture pumpkin glow.
Even then your camera may have issues with auto focus and shutter speed to get the right exposure. You also need to keep in mind most people have trouble holding still when the shutter speed goes below 1/60 and so will you when you are holding a camera. This could result in blurred photos depending what is actually happening when you take the picture, so plan on taking pictures in series too. You may also be combining two different types of light sources together so your camera sensors will only pickup one type...like incandescent. This could impact the color of your photo too.
You will most likely need to shoot in a manual mode to get the right effect by taking a series of photos at different settings. You will also need to have the two subjects close enough so they are in focus (depth of field) which you can control by setting your lense f/stop higher...if your camera allows this. If it doesn't, you will need to bring these two items close together and you may want to reference your camera manual for guidance.
It is possible to take a picture under the conditions you have described, but you should plan on experimenting until you find the right combination of the items I mentioned above. It gets easier and easier each time you shoot these types of situations and the results will make you want to exisiting light situations more and more.
