When Jesus was on the cross what do you suppose was going on in Heaven? One thing my Dad believed you would have seen was God holding on to the Archangel Michael's harness (the straps across his back that held his breastplate on) to keep him from going to help Him. I think an indication of what may have been going on, while The Lord was on the cross over 3 hours, is found in Exodus 12 and Job Chapters 1 & 2.
First of all we need to look at the first Passover in Egypt (Exodus 12). The Lord's instructions to Moses and Aaron was to have each family take a yearling male lamb or kid, without blemish, and shut it up from the 10th of the month until the 14th, then kill it. The purpose of this 3+ day period was to make sure there wasn't anything wrong with it. You might say the lamb was being tested to make sure it was without blemish.
In Job we are informed that Satan has, or at one time had, access to God's throne. Whether he can still go there, what he does there, why he goes there, or how often, we can only speculate, but on those two occasions in Job he was trying to find fault with a "perfect and upright" man. Remember that he is no stranger to God's throne. He was created as Lucifer (morning star), called "son of the morning" in Isaiah 14:12. Ezekiel calls him "the anointed cherub that covereth" (Ez. 28:14) and "the covering cherub" (Ez. 28:16). Covereth and covering is the same Hebrew word, meaning "to entwine (or screen), to fence in, to cover over, or to protect." An indication of his original role in Heaven can be seen in the description of the Ark of the Covenant, Israel's holiest artifact in the Holy of Holies in the Tabernacle and later in Solomon's Temple. It was a gold-plated box with a pure gold lid called The Mercy Seat. Mounted on this mercy seat were two golden cherubs. Exodus 25:40 says God showed Moses a "pattern" when he was on the mount so he would know exactly what it was supposed to look like. The implication is clear that Satan's role as Lucifer in the beginning was to cover and protect the real Mercy Seat located in God's throne in Heaven.
Now back to the cross. We're not told exactly what time that morning He was crucified, but Luke 23:44 says He was on the cross at noon, and that He died just after 3 P.M. During that time I think "The Lamb" was "shut up," and Satan was at God's throne bringing up everything he could think of that would be a blemish and disqualify Jesus as the Passover sacrifice. You can see the scenario through Jesus' words He used while hanging there. He starts out calling God "Father." The trial in Heaven must have started about noon because it becomes dark in the middle of the day. When no fault is found in Him and God imputes the sin of the world onto Him He cries out "My God, My God (not Father), why hast thou forsaken me?" The word forsaken means to leave behind or to desert. Their fellowship had been broken because God cannot look upon sin without judgment, and at that point God is judging Him for the sin of the world. As soon as the atonement for sin has been completed the fellowship is restored and His last words are - - "Father, it is finished." His blood is now over the door posts and lintel of every believer's heart and God can Pass Over our sins. At that time John records He "bowed His head and gave up the ghost."