I am trying to explain Ravi's questions on Draupadi's sons and Karna. It is possible to write like this on each and every character but would usually end up boring to those who read. This is just an example of how deep the story and meanings embedded in it are.
Draupadi is the daughter of Drupada who himself stands for extreme urgency. 'Dru' is to run or hasten and pada is pace or step - in other words one whose pace is quick or swift or indicates extreme urgency/dispassion.Draupadi representds the spiritual power or feeling of kundalini - when kundalini is 'lifted upward' or 'wedded' to the five pandavas who are the creative vibratory elements and consciousness in the five spinal centers she gives birth to five sons who represent the union of divine energy with five elements or in other word dharmic product. The sons of Draupadi are the manifestations of the five opened and awakened spinal centers upon which the yogi concentrates to draw divine discriminatory power to fight the sense mind.
The name KArna derives from the sanskrit root kri 'to do, to work'. In simple terms the word means attachement to work or habitual actions. Karna is half brother to pandavas, their common mother is Kunti, who before her marriage to Pandu used her divinely given power to invoke Surya. Kunti - the power of invoking spiritual energy, begets an offspring from the sun, the light of the spiritual eye, the light from which the whole body of man evolves. However the power of invoking spiritual energy in order to be productive has to united with the power of discriminitory dharmic action (Pandu) - since Karna is born before Kunti is united with Pandu he signifies a helpless attachment to material actions as is Karna in siding with Duryodhana. Karna in principle is the deluded man that causes him to see work or action to which he is attached because of the pleasure it gives him. He justifies the action as his duty but is unable to separate his dharma from it (unlike Vibheeshana of the Ramayana).
There is an exact almost amazing correlation between the Yoga Sutras of Patanjali and the battle of the Mahabharat as seen Allegorically as well as as described in the shlokas of the Gita. This correlation has been examined in great detail by Adi Shankara, and later by Paramhamsa Yogananda.