In my perspective, there are many things which are impossible for the Mahadev..
- Taking anything, since He is the giver. As a sacrificing father to the entire Universe, He caters to the need of all living beings and provides them all luxuries and He resides in the burial ground.
- To see the pain and sufferings of His devotees, so He rushes to their rescue at mere calling His name “ Shiva”.
- Shiva doesn't punish any living being, instead He makes them realise their mistakes through realization and takes away their arrogance, greed and lust.
- Shiva can't stay away from His devotees, since He has the utmost love towards them and treats them as family, so He is always concerned about their well being.
- Shiva doesn't like to wear expensive jewelry and clothes, since He knows that they all are perishable, so it's impossible to convince Shiva and keep Him in the material world.
- Shiva can never say no to any Devotee's wish and grants them all the desired boons, irrespective of whether they are devas or demons.
- Shiva can never stay calm when the Universe and all the living beings are at risk, so as the saviour He drank the Halahal ( poison) that oozed out of the Samudra Manthan, churning of the milk ocean for celestial nectar.
- Shiva can't ignore anyone who is commenting or abusing His beloved Shri Vishnu or any of His avatars. So at times He disciplines them. That is why when King Ravana turned against Shri Rama, God Shiva stopped supporting him, even though he was His greatest devotee.
- Shiva can't be away from His Samadhi or His deep meditation. It's impossible to keep God Shiva busy in worldly affairs.
- Shiva can't be selfish even towards His own family, so He punishes when they do things out of ignorance, since He feels what is required is only dharma, so everyone has to abide to it. That is why God Shiva beheaded His own son, Lord Ganesh.