Sentence 1: We were worried my cat would not get along with our new kitten. 
 Sentence 3: We heard a racket in the middle of the night 
 Sentence 4:  The cats were playing with each other 
 Sentence 5:  They are now best friends and play together all the time 
 Option 1: My cat would hide all day long since the kitten showed up. 
 Option 2: But they became fast friends right away.