Ethereum is the best partner of bitcoin, during 2017 ethereum prices were around 5% of the price of bitcoin. when the bitcoin price is $ 5600 then the ethereum price is $ 280
But why since 2018 until now when bitcoin has reached $ 11 707, ethereum is still $ 227. The ethereum price should be $ 585.
What happened

if bitcoin price is $ 20 000 then ethereum price is only $ 600

There is no pattern between the price of Bitcoin and the price of Ethereum, they are not interconnected. The price is affected primarily by the demand for these coins. It so happened that in the current market, Bitcoin is more popular with investors than Ethereum and that is why the imbalance in their prices went beyond the price ratio so familiar to everyone.