How Do They Get Along?

Lucas and Chloe are getting good with each other. They adore each other and sometimes they get into each other nerves, which I suppose is normal. Some interesting incidents.

Chloe was crawling towards the wires and power point.
Me: Chloe, come here. Don't go to the fan.
Chloe: {stopped to look at me momentarily and continued crawling}
Lucas: Chloe, don't go there.
Chloe: {continued crawling to her destination}
Lucas: {wrap both his arms on Chloe's stomach to prevent her from going further}
Chloe: arg-blah blah {protested}

When Lucas snatched a toy from Chloe.
Lucas: Ch-loe. Don't take that.
Chloe: {could not be bothered}
Lucas: {snatched the toy away from Chloe}
Chloe: arg-blah blah {protested and pulled Lucas' hair}
Lucas: Ch-loe, you are such naughty and stubborn.

I was about to feed Chloe medicine for her cough and wheezing.
Lucas: {started sobbing} Mommy, Chloe doesn't like that.
Me: But Chloe needs it. She is sick.
Lucas: {took the medicine and out it far away from me}
Me: Lucas, please give me the medicine.
Lucas: No, I said Chloe doesn't like that. {still sobbing}

When Chloe is awake in the morning.
Chloe: {sit on her babycot facing the door}
Lucas: {started talking and open her room's door}
Chloe: {stand up and get very excited}
Lucas: Good morning, Chloe
Chloe: {dancing happily and gave her brother a big smile}